diff --git a/ConsoleDemo/PrettyPrinter.cs b/ConsoleDemo/PrettyPrinter.cs
index 585a1c8..1f2be12 100644
--- a/ConsoleDemo/PrettyPrinter.cs
+++ b/ConsoleDemo/PrettyPrinter.cs
@@ -196,7 +196,12 @@ namespace ProjectConsole
             Visit(node.InputDescription);
             Visit(node.Commas);
             Visit(node.Body);
-            OutputKeyword(node.EndKeyword);            
+            Visit(node.EndKeyword);
+        }
+
+        public override void VisitEndKeyword(EndKeywordSyntaxNode node)
+        {
+            OutputKeyword(node.EndKeyword);
         }
 
         public override void VisitFunctionDeclaration(FunctionDeclarationSyntaxNode node)
@@ -207,7 +212,7 @@ namespace ProjectConsole
             Visit(node.InputDescription);
             Visit(node.Commas);
             Visit(node.Body);
-            OutputKeyword(node.EndKeyword);
+            Visit(node.EndKeyword);
         }
 
         public override void VisitIfStatement(IfStatementSyntaxNode node)
diff --git a/Parser/ChildNodesAndTokensList.cs b/Parser/ChildNodesAndTokensList.cs
index 59de5f9..a50ed30 100644
--- a/Parser/ChildNodesAndTokensList.cs
+++ b/Parser/ChildNodesAndTokensList.cs
@@ -68,7 +68,7 @@ namespace Parser
         internal SyntaxNodeOrToken ThisInternal(int index)
         {
             var currentSlotIndex = 0;
-            GreenNode currentSlot = null;
+            GreenNode? currentSlot = null;
             while (true)
             {
                 currentSlot = _node._green.GetSlot(currentSlotIndex);
@@ -84,13 +84,17 @@ namespace Parser
                     if (currentSlot.IsList)
                     {
                         var listSlot = _node.GetNode(currentSlotIndex);
+                        if (listSlot is null)
+                        {
+                            throw new Exception($"Unexpected null in list slot.");
+                        }
                         var red = listSlot.GetNode(index);
-                        if (red != null)
+                        if (!(red is null))
                         {
                             return red;
                         }
                         // this is a token
-                        return new SyntaxToken(listSlot, listSlot._green.GetSlot(index), _node.GetChildPosition(index));
+                        return new SyntaxToken(listSlot, listSlot._green.GetSlot(index)!, _node.GetChildPosition(index));
                     }
                     else
                     {
@@ -100,7 +104,7 @@ namespace Parser
                             return red;
                         }
                         // this is a token
-                        return new SyntaxToken(_node, _node._green.GetSlot(currentSlotIndex), _node.GetChildPosition(currentSlotIndex));
+                        return new SyntaxToken(_node, _node._green.GetSlot(currentSlotIndex)!, _node.GetChildPosition(currentSlotIndex));
                     }
                 }
 
diff --git a/Parser/Internal/Diagnostic.cs b/Parser/Internal/Diagnostic.cs
index cb20f77..dbe5ed4 100644
--- a/Parser/Internal/Diagnostic.cs
+++ b/Parser/Internal/Diagnostic.cs
@@ -4,7 +4,7 @@ namespace Parser.Internal
 {
     public class Diagnostic
     {
-        public TextSpan Span { get; }
+        public TextSpan? Span { get; }
         public string Message { get; }
 
         public Diagnostic(TextSpan span, string message)
@@ -12,5 +12,10 @@ namespace Parser.Internal
             Span = span;
             Message = message ?? throw new ArgumentNullException(nameof(message));
         }
+
+        public Diagnostic(string message)
+        {
+            Message = message ?? throw new ArgumentNullException(nameof(message));
+        }
     }
 }
\ No newline at end of file
diff --git a/Parser/Internal/DiagnosticsBag.cs b/Parser/Internal/DiagnosticsBag.cs
index 39f0fdc..ca0ab3f 100644
--- a/Parser/Internal/DiagnosticsBag.cs
+++ b/Parser/Internal/DiagnosticsBag.cs
@@ -26,6 +26,12 @@ namespace Parser.Internal
             _diagnostics.Add(diagnostic);
         }
 
+        private void Report(string message)
+        {
+            var diagnostic = new Diagnostic(message);
+            _diagnostics.Add(diagnostic);
+        }
+
         internal void ReportUnexpectedEndOfFile(TextSpan span)
         {
             Report(span, "Unexpected end of file.");
@@ -46,9 +52,9 @@ namespace Parser.Internal
             Report(span, $"Unknown symbol '{c}'.");
         }
 
-        internal void ReportUnexpectedToken(TextSpan span, TokenKind expected, TokenKind actual)
+        internal void ReportUnexpectedToken(TokenKind expected, TokenKind actual)
         {
-            Report(span, $"Unexpected token '{actual}', expected '{expected}'.");
+            Report($"Unexpected token '{actual}', expected '{expected}'.");
         }
 
         public IEnumerator<Diagnostic> GetEnumerator()
diff --git a/Parser/Internal/GreenNode.cs b/Parser/Internal/GreenNode.cs
index f938acc..502fb1a 100644
--- a/Parser/Internal/GreenNode.cs
+++ b/Parser/Internal/GreenNode.cs
@@ -10,7 +10,7 @@ namespace Parser.Internal
     {
         public TokenKind Kind { get; }
         public int Slots { get; protected set; }
-        public abstract GreenNode GetSlot(int i);
+        public abstract GreenNode? GetSlot(int i);
 
         public GreenNode(TokenKind kind)
         {
@@ -29,7 +29,7 @@ namespace Parser.Internal
 
         public int FullWidth => _fullWidth;
 
-        protected void AdjustWidth(GreenNode node)
+        protected void AdjustWidth(GreenNode? node)
         {
             if (!(node is null))
             {
@@ -109,12 +109,12 @@ namespace Parser.Internal
             return -1;
         }
 
-        private GreenNode GetFirstTerminal()
+        private GreenNode? GetFirstTerminal()
         {
             var current = this;
             while (true)
             {
-                GreenNode next = null;
+                GreenNode? next = null;
                 if (current.Slots == 0)
                 {
                     return current;
@@ -141,12 +141,12 @@ namespace Parser.Internal
             }
         }
 
-        private GreenNode GetLastTerminal()
+        private GreenNode? GetLastTerminal()
         {
             var current = this;
             while (true)
             {
-                GreenNode next = null;
+                GreenNode? next = null;
                 if (current.Slots == 0)
                 {
                     return current;
diff --git a/Parser/Internal/MLexerGreen.cs b/Parser/Internal/MLexerGreen.cs
index e896b0f..8ff6352 100644
--- a/Parser/Internal/MLexerGreen.cs
+++ b/Parser/Internal/MLexerGreen.cs
@@ -9,9 +9,9 @@ namespace Parser.Internal
     {
         private class TokenInfo
         {
-            public TokenKind Kind { get; set; }
-            public string Text { get; set; }
-            public string StringValue { get; set; }
+            public TokenKind Kind { get; set; } = TokenKind.None;
+            public string Text { get; set; } = "";
+            public string StringValue { get; set; } = "";
             public double DoubleValue { get; set; }
         }
 
@@ -25,6 +25,7 @@ namespace Parser.Internal
         public MLexerGreen(ITextWindow window)
         {
             Window = window;
+            LastToken = SyntaxToken.NoneToken;
             TokenStack = new Stack<TokenKind>();
         }
 
diff --git a/Parser/Internal/MParserGreen.cs b/Parser/Internal/MParserGreen.cs
index 4db3e52..2460a5c 100644
--- a/Parser/Internal/MParserGreen.cs
+++ b/Parser/Internal/MParserGreen.cs
@@ -33,7 +33,7 @@ namespace Parser.Internal
             var token = CurrentToken;
             if (token.Kind != kind)
             {
-                Diagnostics.ReportUnexpectedToken(token.Span, kind, token.Kind);
+                Diagnostics.ReportUnexpectedToken(kind, token.Kind);
                 return TokenFactory.CreateMissing(kind, null, null);
             }
             _index++;
@@ -55,13 +55,13 @@ namespace Parser.Internal
             var token = CurrentToken;
             if (token.Kind != TokenKind.IdentifierToken)
             {
-                Diagnostics.ReportUnexpectedToken(token.Span, TokenKind.IdentifierToken, token.Kind);
+                Diagnostics.ReportUnexpectedToken(TokenKind.IdentifierToken, token.Kind);
                 return TokenFactory.CreateMissing(TokenKind.IdentifierToken, null, null);
             }
 
             if (token.Text != s)
             {
-                Diagnostics.ReportUnexpectedToken(token.Span, TokenKind.IdentifierToken, token.Kind);
+                Diagnostics.ReportUnexpectedToken(TokenKind.IdentifierToken, token.Kind);
                 return TokenFactory.CreateMissing(TokenKind.IdentifierToken, null, null);
             }
 
@@ -69,7 +69,7 @@ namespace Parser.Internal
             return token;
         }
 
-        private SyntaxToken PossiblyEatIdentifier(string s)
+        private SyntaxToken? PossiblyEatIdentifier(string s)
         {
             var token = CurrentToken;
             if (token.Kind == TokenKind.IdentifierToken && token.Text == s)
@@ -94,7 +94,7 @@ namespace Parser.Internal
                 new List<SyntaxTrivia>());
         }
 
-        private SyntaxList ParseFunctionOutputList()
+        private SyntaxList? ParseFunctionOutputList()
         {
             var outputs = new SyntaxListBuilder();
             var firstToken = true;
@@ -112,7 +112,7 @@ namespace Parser.Internal
             return outputs.ToList();
         }
 
-        private FunctionOutputDescriptionSyntaxNode ParseFunctionOutputDescription()
+        private FunctionOutputDescriptionSyntaxNode? ParseFunctionOutputDescription()
         {
             SyntaxToken assignmentSign;
             var builder = new SyntaxListBuilder();
@@ -180,7 +180,7 @@ namespace Parser.Internal
             return builder.ToList();
         }
 
-        private FunctionInputDescriptionSyntaxNode ParseFunctionInputDescription()
+        private FunctionInputDescriptionSyntaxNode? ParseFunctionInputDescription()
         {
             if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
@@ -206,7 +206,8 @@ namespace Parser.Internal
             var inputDescription = ParseFunctionInputDescription();
             var commas = ParseOptionalCommas();
             var body = ParseStatementList();
-            var endKeyword = EatPossiblyMissingIdentifier("end");
+            var endKeyword = ParseEndKeyword();
+            //var endKeyword = 
             return Factory.FunctionDeclarationSyntax(
                 functionKeyword,
                 outputDescription,
@@ -216,7 +217,13 @@ namespace Parser.Internal
                 body,
                 endKeyword);
         }
-       
+
+        private EndKeywordSyntaxNode? ParseEndKeyword()
+        {
+            var keyword = EatPossiblyMissingIdentifier("end");
+            return keyword is null ? null : Factory.EndKeywordSyntax(keyword);
+        }
+
         internal struct ParseOptions
         {
             public bool ParsingArrayElements { get; set; }
@@ -224,12 +231,12 @@ namespace Parser.Internal
             public static ParseOptions Default = new ParseOptions { ParsingArrayElements = false };
         }
 
-        private ExpressionSyntaxNode ParseExpression()
+        private ExpressionSyntaxNode? ParseExpression()
         {
             return ParseExpression(ParseOptions.Default);
         }
 
-        private ExpressionSyntaxNode ParseExpression(ParseOptions options)
+        private ExpressionSyntaxNode? ParseExpression(ParseOptions options)
         {
             return ParseSubExpression(options, SyntaxFacts.Precedence.Expression);
         }
@@ -286,10 +293,10 @@ namespace Parser.Internal
             return builder.ToList();
         }
 
-        private ExpressionSyntaxNode ParseTerm(ParseOptions options)
+        private ExpressionSyntaxNode? ParseTerm(ParseOptions options)
         {
             var token = CurrentToken;
-            ExpressionSyntaxNode expression = null;
+            ExpressionSyntaxNode? expression = null;
             switch (token.Kind)
             {
                 case TokenKind.NumberLiteralToken:
@@ -410,6 +417,11 @@ namespace Parser.Internal
 
                 return Factory.CommandExpressionSyntax(idNameNode, builder.ToList());
             }
+
+            if (expression is null)
+            {
+                throw new Exception("Command expression identifier cannot be empty.");
+            }
             throw new ParsingException($"Unexpected token \"{CurrentToken}\" while parsing expression \"{expression.FullText}\" at {CurrentPosition}.");
         }
 
@@ -420,6 +432,10 @@ namespace Parser.Internal
             {
                 var atToken = EatToken();
                 var baseClassNameWithArguments = ParseExpression();
+                if (baseClassNameWithArguments is null)
+                {
+                    throw new Exception($"Base class name cannot be empty.");
+                }
                 return Factory.BaseClassInvokationSyntax(methodName, atToken, baseClassNameWithArguments);
             }
             if (expression is MemberAccessSyntaxNode memberAccess
@@ -427,6 +443,10 @@ namespace Parser.Internal
             {
                 var atToken = EatToken();
                 var baseClassNameWithArguments = ParseExpression();
+                if (baseClassNameWithArguments is null)
+                {
+                    throw new Exception($"Base class name cannot be empty.");
+                }
                 return Factory.BaseClassInvokationSyntax(memberAccess, atToken, baseClassNameWithArguments);
             }
             throw new ParsingException($"Unexpected token \"{CurrentToken}\" at {CurrentPosition}.");
@@ -442,6 +462,10 @@ namespace Parser.Internal
             {
                 var openingBracket = EatToken();
                 var indirectMember = ParseExpression();
+                if (indirectMember is null)
+                {
+                    throw new Exception("Indirect member invokation cannot be empty.");
+                }
                 var closingBracket = EatToken(TokenKind.CloseParenthesisToken);
                 return Factory.IndirectMemberAccessSyntax(
                     openingBracket,
@@ -466,7 +490,12 @@ namespace Parser.Internal
                     firstToken = false;
                 }
 
-                builder.Add(ParseExpression());
+                var expression = ParseExpression();
+                if (expression is null)
+                {
+                    throw new Exception("Function call parameter cannot be empty.");
+                }
+                builder.Add(expression);
             }
 
             return builder.ToList();
@@ -476,6 +505,10 @@ namespace Parser.Internal
         {
             var openParen = EatToken(TokenKind.OpenParenthesisToken);
             var expression = ParseExpression();
+            if (expression is null)
+            {
+                throw new Exception("Parenthesized expression cannot be empty.");
+            }
             var closeParen = EatToken(TokenKind.CloseParenthesisToken);
             return Factory.ParenthesizedExpressionSyntax(
                 openParen,
@@ -514,17 +547,25 @@ namespace Parser.Internal
             else if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
                 var inputs = ParseFunctionInputDescription();
+                if (inputs is null)
+                {
+                    throw new Exception($"Lambda expression inputs cannot be empty.");
+                }
                 var body = ParseExpression();
+                if (body is null)
+                {
+                    throw new Exception($"Lambda expression body cannot be empty.");
+                }
                 return Factory.LambdaSyntax(atSign, inputs, body);
             }
             throw new ParsingException($"Unexpected token {CurrentToken} while parsing function handle at {CurrentPosition}.");
         }
 
-        private ExpressionSyntaxNode ParseSubExpression(
+        private ExpressionSyntaxNode? ParseSubExpression(
             ParseOptions options,
             SyntaxFacts.Precedence precedence)
         {
-            ExpressionSyntaxNode lhs;
+            ExpressionSyntaxNode? lhs;
             if (SyntaxFacts.IsUnaryOperator(CurrentToken.Kind))
             {
                 var operation = EatToken();
@@ -551,6 +592,10 @@ namespace Parser.Internal
             else
             {
                 lhs = ParseTerm(options);
+                if (lhs is null)
+                {
+                    throw new Exception("Left-hand side in subexpression cannot be empty.");
+                }
             }
 
             while (true)
@@ -579,9 +624,10 @@ namespace Parser.Internal
                         }
                         else
                         {
-                            rhs = null;
+                            throw new Exception("Right-hand side in subexpression cannot be empty.");
                         }
                     }
+                    
                     if (token.Kind == TokenKind.EqualsToken)
                     {
                         lhs = Factory.AssignmentExpressionSyntax(lhs, token, rhs);
@@ -627,6 +673,10 @@ namespace Parser.Internal
         {
             var caseKeyword = EatIdentifier("case");
             var caseId = ParseExpression();
+            if (caseId is null)
+            {
+                throw new Exception("Case label cannot be empty.");
+            }
             var commas = ParseOptionalCommas();
             var statementList = ParseStatementList();
             return Factory.SwitchCaseSyntax(caseKeyword, caseId, commas, statementList);
@@ -636,6 +686,10 @@ namespace Parser.Internal
         {
             var switchKeyword = EatIdentifier("switch");
             var expression = ParseExpression();
+            if (expression is null)
+            {
+                throw new Exception("Match expression in switch statement cannot be empty.");
+            }
             var commas = ParseOptionalCommas();
             var builder = new SyntaxListBuilder<SwitchCaseSyntaxNode>();
             while (IsIdentifier(CurrentToken, "case"))
@@ -655,6 +709,11 @@ namespace Parser.Internal
         {
             var whileKeyword = EatIdentifier("while");
             var condition = ParseExpression();
+            if (condition is null)
+            {
+                throw new Exception("Condition in while statement cannot be empty.");
+            }
+
             var commas = ParseOptionalCommas();
             var body = ParseStatementList();
             var endKeyword = EatIdentifier("end");
@@ -670,6 +729,10 @@ namespace Parser.Internal
         {
             var elseifKeyword = EatIdentifier("elseif");
             var condition = ParseExpression();
+            if (condition is null)
+            {
+                throw new Exception("Condition in elseif clause cannot be empty.");
+            }
             var commas = ParseOptionalCommas();
             var body = ParseStatementList();
             return Factory.ElseifClause(elseifKeyword, condition, commas, body);
@@ -686,10 +749,14 @@ namespace Parser.Internal
         {
             var ifKeyword = EatIdentifier();
             var condition = ParseExpression();
+            if (condition is null)
+            {
+                throw new Exception("Condition in if statement cannot be empty.");
+            }
             var commas = ParseOptionalSemicolonsOrCommas();
             var body = ParseStatementList();
             var elseifClauses = new SyntaxListBuilder<ElseifClause>();
-            ElseClause elseClause = null;
+            ElseClause? elseClause = null;
             while (true)
             {
                 var token = CurrentToken;
@@ -740,7 +807,7 @@ namespace Parser.Internal
                 endKeyword);
         }
 
-        private CatchClauseSyntaxNode ParseCatchClause()
+        private CatchClauseSyntaxNode? ParseCatchClause()
         {
             if (IsIdentifier(CurrentToken, "catch"))
             {
@@ -766,15 +833,24 @@ namespace Parser.Internal
         private ExpressionStatementSyntaxNode ParseExpressionStatement()
         {
             var expression = ParseExpression();
+            if (expression is null)
+            {
+                throw new Exception("Expression statement cannot be empty.");
+            }
+
             return Factory.ExpressionStatementSyntax(expression);
         }
 
-        private AttributeAssignmentSyntaxNode ParseAttributeAssignment()
+        private AttributeAssignmentSyntaxNode? ParseAttributeAssignment()
         {
             if (CurrentToken.Kind == TokenKind.EqualsToken)
             {
                 var assignmentSign = EatToken();
                 var value = ParseExpression();
+                if (value is null)
+                {
+                    throw new Exception("Right-hand side in attribute assignment cannot be empty.");
+                }
                 return Factory.AttributeAssignmentSyntax(assignmentSign, value);
             }
 
@@ -845,7 +921,7 @@ namespace Parser.Internal
             var inputDescription = ParseFunctionInputDescription();
             var commas = ParseOptionalCommas();
             var body = ParseStatementList();
-            var endKeyword = PossiblyEatIdentifier("end");
+            var endKeyword = ParseEndKeyword();
             return Factory.MethodDefinitionSyntax(
                 functionKeyword,
                 outputDescription,
@@ -859,7 +935,7 @@ namespace Parser.Internal
         private MethodsListSyntaxNode ParseMethods()
         {
             var methodsKeyword = EatToken();
-            AttributeListSyntaxNode attributes = null;
+            AttributeListSyntaxNode? attributes = null;
             if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
                 attributes = ParseAttributesList();
@@ -876,7 +952,7 @@ namespace Parser.Internal
             return Factory.MethodsListSyntax(methodsKeyword, attributes, builder.ToList(), endKeyword);
         }
 
-        private GreenNode ParsePropertyDeclaration()
+        private GreenNode? ParsePropertyDeclaration()
         {
             if (CurrentToken.Kind == TokenKind.CommaToken)
             {
@@ -885,7 +961,7 @@ namespace Parser.Internal
             return ParseStatement();
         }
 
-        private SyntaxNode ParseEventDeclaration()
+        private SyntaxNode? ParseEventDeclaration()
         {
             return ParseStatement();
         }
@@ -893,7 +969,7 @@ namespace Parser.Internal
         private PropertiesListSyntaxNode ParseProperties()
         {
             var propertiesKeyword = EatToken();
-            AttributeListSyntaxNode attributes = null;
+            AttributeListSyntaxNode? attributes = null;
             if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
                 attributes = ParseAttributesList();
@@ -902,14 +978,19 @@ namespace Parser.Internal
             var builder = new SyntaxListBuilder();
             while (!IsIdentifier(CurrentToken, "end"))
             {
-                builder.Add(ParsePropertyDeclaration());
+                var declaration = ParsePropertyDeclaration();
+                if (declaration is null)
+                {
+                    throw new Exception("Property declaration cannot be null.");
+                }
+                builder.Add(declaration);
             }
 
             var endKeyword = EatToken();
             return Factory.PropertiesListSyntax(propertiesKeyword, attributes, builder.ToList(), endKeyword);
         }
 
-        private EnumerationItemValueSyntaxNode ParseEnumerationValue()
+        private EnumerationItemValueSyntaxNode? ParseEnumerationValue()
         {
             if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
@@ -920,7 +1001,12 @@ namespace Parser.Internal
                 while (CurrentToken.Kind == TokenKind.CommaToken)
                 {
                     builder.Add(EatToken());
-                    builder.Add(ParseExpression());
+                    var nextExpression = ParseExpression();
+                    if (nextExpression is null)
+                    {
+                        throw new Exception("Enumeration identifier cannot be empty.");
+                    }
+                    builder.Add(nextExpression);
                 }
                 var closingBracket = EatToken(TokenKind.CloseParenthesisToken);
                 return Factory.EnumerationItemValueSyntax(openingBracket, builder.ToList(), closingBracket);
@@ -940,7 +1026,7 @@ namespace Parser.Internal
         {
             var enumerationKeyword = EatToken();
             var builder = new SyntaxListBuilder<EnumerationItemSyntaxNode>();
-            AttributeListSyntaxNode attributes = null;
+            AttributeListSyntaxNode? attributes = null;
             if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
                 attributes = ParseAttributesList();
@@ -962,7 +1048,7 @@ namespace Parser.Internal
         private SyntaxNode ParseEvents()
         {
             var eventsKeyword = EatToken();
-            AttributeListSyntaxNode attributes = null;
+            AttributeListSyntaxNode? attributes = null;
             if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
                 attributes = ParseAttributesList();
@@ -971,7 +1057,12 @@ namespace Parser.Internal
             var builder = new SyntaxListBuilder();
             while (!IsIdentifier(CurrentToken, "end"))
             {
-                builder.Add(ParseEventDeclaration());
+                var eventDeclaration = ParseEventDeclaration();
+                if (eventDeclaration is null)
+                {
+                    throw new Exception("Event declaration cannot be empty.");
+                }
+                builder.Add(eventDeclaration);
             }
 
             var endKeyword = EatToken();
@@ -1001,13 +1092,13 @@ namespace Parser.Internal
         private StatementSyntaxNode ParseClassDeclaration()
         {
             var classdefKeyword = EatToken();
-            AttributeListSyntaxNode attributes = null;
+            AttributeListSyntaxNode? attributes = null;
             if (CurrentToken.Kind == TokenKind.OpenParenthesisToken)
             {
                 attributes = ParseAttributesList();
             }
             var className = Factory.IdentifierNameSyntax(EatToken(TokenKind.IdentifierToken));
-            BaseClassListSyntaxNode baseClassList = null;
+            BaseClassListSyntaxNode? baseClassList = null;
             if (CurrentToken.Kind == TokenKind.LessToken)
             {
                 baseClassList = ParseBaseClassList();
@@ -1052,7 +1143,7 @@ namespace Parser.Internal
                 endKeyword);
         }
 
-        private StatementSyntaxNode ParseStatement()
+        private StatementSyntaxNode? ParseStatement()
         {
             if (CurrentToken.Kind == TokenKind.IdentifierToken)
             {
@@ -1120,5 +1211,11 @@ namespace Parser.Internal
             var endOfFileToken = EatToken();
             return Factory.FileSyntax(statementList, endOfFileToken);
         }
+
+        public RootSyntaxNode ParseRoot()
+        {
+            var file = ParseFile();
+            return Factory.RootSyntax(file);
+        }
     }
 }
\ No newline at end of file
diff --git a/Parser/Internal/SyntaxFactory.Generated.cs b/Parser/Internal/SyntaxFactory.Generated.cs
index b6f42c2..6652d9a 100644
--- a/Parser/Internal/SyntaxFactory.Generated.cs
+++ b/Parser/Internal/SyntaxFactory.Generated.cs
@@ -13,12 +13,12 @@ namespace Parser.Internal
 
         public FunctionDeclarationSyntaxNode FunctionDeclarationSyntax(
             SyntaxToken functionKeyword, 
-            FunctionOutputDescriptionSyntaxNode outputDescription, 
+            FunctionOutputDescriptionSyntaxNode? outputDescription, 
             SyntaxToken name, 
-            FunctionInputDescriptionSyntaxNode inputDescription, 
+            FunctionInputDescriptionSyntaxNode? inputDescription, 
             SyntaxList<SyntaxToken> commas, 
             SyntaxList body, 
-            SyntaxToken endKeyword)
+            EndKeywordSyntaxNode? endKeyword)
         {
             return new FunctionDeclarationSyntaxNode(
                 functionKeyword, 
@@ -121,7 +121,7 @@ namespace Parser.Internal
             SyntaxList<SyntaxToken> optionalCommas, 
             SyntaxList body, 
             SyntaxList<ElseifClause> elseifClauses, 
-            ElseClause elseClause, 
+            ElseClause? elseClause, 
             SyntaxToken endKeyword)
         {
             return new IfStatementSyntaxNode(
@@ -172,7 +172,7 @@ namespace Parser.Internal
         public TryCatchStatementSyntaxNode TryCatchStatementSyntax(
             SyntaxToken tryKeyword, 
             SyntaxList tryBody, 
-            CatchClauseSyntaxNode catchClause, 
+            CatchClauseSyntaxNode? catchClause, 
             SyntaxToken endKeyword)
         {
             return new TryCatchStatementSyntaxNode(
@@ -404,7 +404,7 @@ namespace Parser.Internal
 
         public AttributeSyntaxNode AttributeSyntax(
             IdentifierNameSyntaxNode name, 
-            AttributeAssignmentSyntaxNode assignment)
+            AttributeAssignmentSyntaxNode? assignment)
         {
             return new AttributeSyntaxNode(
                 name, 
@@ -424,12 +424,12 @@ namespace Parser.Internal
 
         public MethodDefinitionSyntaxNode MethodDefinitionSyntax(
             SyntaxToken functionKeyword, 
-            FunctionOutputDescriptionSyntaxNode outputDescription, 
+            FunctionOutputDescriptionSyntaxNode? outputDescription, 
             CompoundNameSyntaxNode name, 
-            FunctionInputDescriptionSyntaxNode inputDescription, 
+            FunctionInputDescriptionSyntaxNode? inputDescription, 
             SyntaxList<SyntaxToken> commas, 
             SyntaxList body, 
-            SyntaxToken endKeyword)
+            EndKeywordSyntaxNode? endKeyword)
         {
             return new MethodDefinitionSyntaxNode(
                 functionKeyword, 
@@ -442,9 +442,9 @@ namespace Parser.Internal
         }
 
         public AbstractMethodDeclarationSyntaxNode AbstractMethodDeclarationSyntax(
-            FunctionOutputDescriptionSyntaxNode outputDescription, 
+            FunctionOutputDescriptionSyntaxNode? outputDescription, 
             CompoundNameSyntaxNode name, 
-            FunctionInputDescriptionSyntaxNode inputDescription)
+            FunctionInputDescriptionSyntaxNode? inputDescription)
         {
             return new AbstractMethodDeclarationSyntaxNode(
                 outputDescription, 
@@ -454,7 +454,7 @@ namespace Parser.Internal
 
         public MethodsListSyntaxNode MethodsListSyntax(
             SyntaxToken methodsKeyword, 
-            AttributeListSyntaxNode attributes, 
+            AttributeListSyntaxNode? attributes, 
             SyntaxList methods, 
             SyntaxToken endKeyword)
         {
@@ -467,7 +467,7 @@ namespace Parser.Internal
 
         public PropertiesListSyntaxNode PropertiesListSyntax(
             SyntaxToken propertiesKeyword, 
-            AttributeListSyntaxNode attributes, 
+            AttributeListSyntaxNode? attributes, 
             SyntaxList properties, 
             SyntaxToken endKeyword)
         {
@@ -489,9 +489,9 @@ namespace Parser.Internal
 
         public ClassDeclarationSyntaxNode ClassDeclarationSyntax(
             SyntaxToken classdefKeyword, 
-            AttributeListSyntaxNode attributes, 
+            AttributeListSyntaxNode? attributes, 
             IdentifierNameSyntaxNode className, 
-            BaseClassListSyntaxNode baseClassList, 
+            BaseClassListSyntaxNode? baseClassList, 
             SyntaxList nodes, 
             SyntaxToken endKeyword)
         {
@@ -517,7 +517,7 @@ namespace Parser.Internal
 
         public EnumerationItemSyntaxNode EnumerationItemSyntax(
             IdentifierNameSyntaxNode name, 
-            EnumerationItemValueSyntaxNode values, 
+            EnumerationItemValueSyntaxNode? values, 
             SyntaxList<SyntaxToken> commas)
         {
             return new EnumerationItemSyntaxNode(
@@ -528,7 +528,7 @@ namespace Parser.Internal
 
         public EnumerationListSyntaxNode EnumerationListSyntax(
             SyntaxToken enumerationKeyword, 
-            AttributeListSyntaxNode attributes, 
+            AttributeListSyntaxNode? attributes, 
             SyntaxList<EnumerationItemSyntaxNode> items, 
             SyntaxToken endKeyword)
         {
@@ -541,7 +541,7 @@ namespace Parser.Internal
 
         public EventsListSyntaxNode EventsListSyntax(
             SyntaxToken eventsKeyword, 
-            AttributeListSyntaxNode attributes, 
+            AttributeListSyntaxNode? attributes, 
             SyntaxList events, 
             SyntaxToken endKeyword)
         {
@@ -551,5 +551,12 @@ namespace Parser.Internal
                 events, 
                 endKeyword);
         }
+
+        public EndKeywordSyntaxNode EndKeywordSyntax(
+            SyntaxToken endKeyword)
+        {
+            return new EndKeywordSyntaxNode(
+                endKeyword);
+        }
     }
 }
\ No newline at end of file
diff --git a/Parser/Internal/SyntaxFactory.cs b/Parser/Internal/SyntaxFactory.cs
index 83a9d8b..8c86a6a 100644
--- a/Parser/Internal/SyntaxFactory.cs
+++ b/Parser/Internal/SyntaxFactory.cs
@@ -2,5 +2,9 @@
 {
     internal partial class SyntaxFactory
     {
+        public RootSyntaxNode RootSyntax(FileSyntaxNode file)
+        {
+            return new RootSyntaxNode(file);
+        }
     }
 }
\ No newline at end of file
diff --git a/Parser/Internal/SyntaxFacts.cs b/Parser/Internal/SyntaxFacts.cs
index b2f6c1d..4fd28ca 100644
--- a/Parser/Internal/SyntaxFacts.cs
+++ b/Parser/Internal/SyntaxFacts.cs
@@ -155,7 +155,7 @@ namespace Parser.Internal
             }
         }
 
-        private static readonly string[] StringFromKind =
+        private static readonly string?[] StringFromKind =
         {
             null, // None = 0,
             null, // BadToken = 1,
@@ -210,7 +210,7 @@ namespace Parser.Internal
             "?", // UnaryQuestionMark = 60,
         };
         
-        public static string GetText(TokenKind kind)
+        public static string? GetText(TokenKind kind)
         {
             if ((int) kind < (int) TokenKind.File)
             {
diff --git a/Parser/Internal/SyntaxList.cs b/Parser/Internal/SyntaxList.cs
index 033c143..6699e0a 100644
--- a/Parser/Internal/SyntaxList.cs
+++ b/Parser/Internal/SyntaxList.cs
@@ -17,16 +17,23 @@ namespace Parser.Internal
             }
         }
 
-        public override GreenNode GetSlot(int i)
+        public GreenNode GetListSlot(int i)
         {
             return _elements[i];
         }
 
+        public override GreenNode? GetSlot(int i)
+        {
+            return GetListSlot(i);
+        }
+
         public static SyntaxList List(GreenNode[] elements)
         {
             return new SyntaxList(elements);
         }
 
+        public static SyntaxList EmptyList { get; } = new SyntaxList(new GreenNode[] { });
+
         public override bool IsList => true;
 
         internal override Parser.SyntaxNode CreateRed(Parser.SyntaxNode parent, int position)
diff --git a/Parser/Internal/SyntaxListBuilder.cs b/Parser/Internal/SyntaxListBuilder.cs
index 15567ce..f9f7e04 100644
--- a/Parser/Internal/SyntaxListBuilder.cs
+++ b/Parser/Internal/SyntaxListBuilder.cs
@@ -20,14 +20,14 @@ namespace Parser.Internal
         {
             for (var i = 0; i < list.Slots; i++)
             {
-                var element = list.GetSlot(i);
+                var element = list.GetListSlot(i);
                 _list.Add(element);
             }
         }
 
         public SyntaxList ToList()
         {
-            return _list.Count == 0 ? null : SyntaxList.List(_list.ToArray());
+            return _list.Count == 0 ? SyntaxList.EmptyList : SyntaxList.List(_list.ToArray());
         }
     }
 }
\ No newline at end of file
diff --git a/Parser/Internal/SyntaxListBuilder`1.cs b/Parser/Internal/SyntaxListBuilder`1.cs
index 6f7edb8..db71907 100644
--- a/Parser/Internal/SyntaxListBuilder`1.cs
+++ b/Parser/Internal/SyntaxListBuilder`1.cs
@@ -18,7 +18,7 @@ namespace Parser.Internal
 
         public SyntaxList<T> ToList()
         {
-            return _list.Count == 0 ? null : SyntaxList<T>.List(_list.ToArray());
+            return _list.Count == 0 ? SyntaxList<T>.Empty : SyntaxList<T>.List(_list.ToArray());
         }
 
     }
diff --git a/Parser/Internal/SyntaxList`1.cs b/Parser/Internal/SyntaxList`1.cs
index 2315ffc..3efa41e 100644
--- a/Parser/Internal/SyntaxList`1.cs
+++ b/Parser/Internal/SyntaxList`1.cs
@@ -14,9 +14,9 @@
             }
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
-            return (T)_list.GetSlot(i);
+            return (T)_list.GetListSlot(i);
         }
 
         public static SyntaxList<T> List(T[] elements)
@@ -24,6 +24,8 @@
             return new SyntaxList<T>(elements);
         }
 
+        public static SyntaxList<T> Empty => new SyntaxList<T>(new T[] { });
+
         public override bool IsList => true;
 
         internal override Parser.SyntaxNode CreateRed(Parser.SyntaxNode parent, int position)
diff --git a/Parser/Internal/SyntaxNode.Generated.cs b/Parser/Internal/SyntaxNode.Generated.cs
index baf7e9f..1841cc0 100644
--- a/Parser/Internal/SyntaxNode.Generated.cs
+++ b/Parser/Internal/SyntaxNode.Generated.cs
@@ -9,7 +9,6 @@ namespace Parser.Internal
             SyntaxList statementList,
             SyntaxToken endOfFile) : base(TokenKind.File)
         {
-
             Slots = 2;
             this.AdjustWidth(statementList);
             _statementList = statementList;
@@ -22,7 +21,7 @@ namespace Parser.Internal
             return new Parser.FileSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -36,23 +35,22 @@ namespace Parser.Internal
     internal class FunctionDeclarationSyntaxNode : StatementSyntaxNode
     {
         internal readonly SyntaxToken _functionKeyword;
-        internal readonly FunctionOutputDescriptionSyntaxNode _outputDescription;
+        internal readonly FunctionOutputDescriptionSyntaxNode? _outputDescription;
         internal readonly SyntaxToken _name;
-        internal readonly FunctionInputDescriptionSyntaxNode _inputDescription;
+        internal readonly FunctionInputDescriptionSyntaxNode? _inputDescription;
         internal readonly SyntaxList<SyntaxToken> _commas;
         internal readonly SyntaxList _body;
-        internal readonly SyntaxToken _endKeyword;
+        internal readonly EndKeywordSyntaxNode? _endKeyword;
 
         internal FunctionDeclarationSyntaxNode(
             SyntaxToken functionKeyword,
-            FunctionOutputDescriptionSyntaxNode outputDescription,
+            FunctionOutputDescriptionSyntaxNode? outputDescription,
             SyntaxToken name,
-            FunctionInputDescriptionSyntaxNode inputDescription,
+            FunctionInputDescriptionSyntaxNode? inputDescription,
             SyntaxList<SyntaxToken> commas,
             SyntaxList body,
-            SyntaxToken endKeyword) : base(TokenKind.FunctionDeclaration)
+            EndKeywordSyntaxNode? endKeyword) : base(TokenKind.FunctionDeclaration)
         {
-
             Slots = 7;
             this.AdjustWidth(functionKeyword);
             _functionKeyword = functionKeyword;
@@ -75,7 +73,7 @@ namespace Parser.Internal
             return new Parser.FunctionDeclarationSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -100,7 +98,6 @@ namespace Parser.Internal
             SyntaxList outputList,
             SyntaxToken assignmentSign) : base(TokenKind.FunctionOutputDescription)
         {
-
             Slots = 2;
             this.AdjustWidth(outputList);
             _outputList = outputList;
@@ -113,7 +110,7 @@ namespace Parser.Internal
             return new Parser.FunctionOutputDescriptionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -135,7 +132,6 @@ namespace Parser.Internal
             SyntaxList parameterList,
             SyntaxToken closingBracket) : base(TokenKind.FunctionInputDescription)
         {
-
             Slots = 3;
             this.AdjustWidth(openingBracket);
             _openingBracket = openingBracket;
@@ -150,7 +146,7 @@ namespace Parser.Internal
             return new Parser.FunctionInputDescriptionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -177,7 +173,6 @@ namespace Parser.Internal
             SyntaxList<SwitchCaseSyntaxNode> cases,
             SyntaxToken endKeyword) : base(TokenKind.SwitchStatement)
         {
-
             Slots = 5;
             this.AdjustWidth(switchKeyword);
             _switchKeyword = switchKeyword;
@@ -196,7 +191,7 @@ namespace Parser.Internal
             return new Parser.SwitchStatementSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -223,7 +218,6 @@ namespace Parser.Internal
             SyntaxList<SyntaxToken> optionalCommas,
             SyntaxList body) : base(TokenKind.SwitchCase)
         {
-
             Slots = 4;
             this.AdjustWidth(caseKeyword);
             _caseKeyword = caseKeyword;
@@ -240,7 +234,7 @@ namespace Parser.Internal
             return new Parser.SwitchCaseSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -268,7 +262,6 @@ namespace Parser.Internal
             SyntaxList body,
             SyntaxToken endKeyword) : base(TokenKind.WhileStatement)
         {
-
             Slots = 5;
             this.AdjustWidth(whileKeyword);
             _whileKeyword = whileKeyword;
@@ -287,7 +280,7 @@ namespace Parser.Internal
             return new Parser.WhileStatementSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -314,7 +307,6 @@ namespace Parser.Internal
             SyntaxList<SyntaxToken> optionalCommas,
             SyntaxList body) : base(TokenKind.ElseifClause)
         {
-
             Slots = 4;
             this.AdjustWidth(elseifKeyword);
             _elseifKeyword = elseifKeyword;
@@ -331,7 +323,7 @@ namespace Parser.Internal
             return new Parser.ElseifClause(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -353,7 +345,6 @@ namespace Parser.Internal
             SyntaxToken elseKeyword,
             SyntaxList body) : base(TokenKind.ElseClause)
         {
-
             Slots = 2;
             this.AdjustWidth(elseKeyword);
             _elseKeyword = elseKeyword;
@@ -366,7 +357,7 @@ namespace Parser.Internal
             return new Parser.ElseClause(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -384,7 +375,7 @@ namespace Parser.Internal
         internal readonly SyntaxList<SyntaxToken> _optionalCommas;
         internal readonly SyntaxList _body;
         internal readonly SyntaxList<ElseifClause> _elseifClauses;
-        internal readonly ElseClause _elseClause;
+        internal readonly ElseClause? _elseClause;
         internal readonly SyntaxToken _endKeyword;
 
         internal IfStatementSyntaxNode(
@@ -393,10 +384,9 @@ namespace Parser.Internal
             SyntaxList<SyntaxToken> optionalCommas,
             SyntaxList body,
             SyntaxList<ElseifClause> elseifClauses,
-            ElseClause elseClause,
+            ElseClause? elseClause,
             SyntaxToken endKeyword) : base(TokenKind.IfStatement)
         {
-
             Slots = 7;
             this.AdjustWidth(ifKeyword);
             _ifKeyword = ifKeyword;
@@ -419,7 +409,7 @@ namespace Parser.Internal
             return new Parser.IfStatementSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -450,7 +440,6 @@ namespace Parser.Internal
             SyntaxList body,
             SyntaxToken endKeyword) : base(TokenKind.ForStatement)
         {
-
             Slots = 5;
             this.AdjustWidth(forKeyword);
             _forKeyword = forKeyword;
@@ -469,7 +458,7 @@ namespace Parser.Internal
             return new Parser.ForStatementSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -494,7 +483,6 @@ namespace Parser.Internal
             SyntaxToken assignmentSign,
             ExpressionSyntaxNode rhs) : base(TokenKind.AssignmentExpression)
         {
-
             Slots = 3;
             this.AdjustWidth(lhs);
             _lhs = lhs;
@@ -509,7 +497,7 @@ namespace Parser.Internal
             return new Parser.AssignmentExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -530,7 +518,6 @@ namespace Parser.Internal
             SyntaxToken catchKeyword,
             SyntaxList catchBody) : base(TokenKind.CatchClause)
         {
-
             Slots = 2;
             this.AdjustWidth(catchKeyword);
             _catchKeyword = catchKeyword;
@@ -543,7 +530,7 @@ namespace Parser.Internal
             return new Parser.CatchClauseSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -558,16 +545,15 @@ namespace Parser.Internal
     {
         internal readonly SyntaxToken _tryKeyword;
         internal readonly SyntaxList _tryBody;
-        internal readonly CatchClauseSyntaxNode _catchClause;
+        internal readonly CatchClauseSyntaxNode? _catchClause;
         internal readonly SyntaxToken _endKeyword;
 
         internal TryCatchStatementSyntaxNode(
             SyntaxToken tryKeyword,
             SyntaxList tryBody,
-            CatchClauseSyntaxNode catchClause,
+            CatchClauseSyntaxNode? catchClause,
             SyntaxToken endKeyword) : base(TokenKind.TryCatchStatement)
         {
-
             Slots = 4;
             this.AdjustWidth(tryKeyword);
             _tryKeyword = tryKeyword;
@@ -584,7 +570,7 @@ namespace Parser.Internal
             return new Parser.TryCatchStatementSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -604,7 +590,6 @@ namespace Parser.Internal
         internal ExpressionStatementSyntaxNode(
             ExpressionSyntaxNode expression) : base(TokenKind.ExpressionStatement)
         {
-
             Slots = 1;
             this.AdjustWidth(expression);
             _expression = expression;
@@ -615,7 +600,7 @@ namespace Parser.Internal
             return new Parser.ExpressionStatementSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -632,7 +617,6 @@ namespace Parser.Internal
         internal EmptyStatementSyntaxNode(
             SyntaxToken semicolon) : base(TokenKind.EmptyStatement)
         {
-
             Slots = 1;
             this.AdjustWidth(semicolon);
             _semicolon = semicolon;
@@ -643,7 +627,7 @@ namespace Parser.Internal
             return new Parser.EmptyStatementSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -658,7 +642,6 @@ namespace Parser.Internal
 
         internal EmptyExpressionSyntaxNode() : base(TokenKind.EmptyExpression)
         {
-
             Slots = 0;
         }
 
@@ -667,7 +650,7 @@ namespace Parser.Internal
             return new Parser.EmptyExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -685,7 +668,6 @@ namespace Parser.Internal
             SyntaxToken operation,
             ExpressionSyntaxNode operand) : base(TokenKind.UnaryPrefixOperationExpression)
         {
-
             Slots = 2;
             this.AdjustWidth(operation);
             _operation = operation;
@@ -698,7 +680,7 @@ namespace Parser.Internal
             return new Parser.UnaryPrefixOperationExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -716,7 +698,6 @@ namespace Parser.Internal
         internal CompoundNameSyntaxNode(
             SyntaxList nodes) : base(TokenKind.CompoundName)
         {
-
             Slots = 1;
             this.AdjustWidth(nodes);
             _nodes = nodes;
@@ -727,7 +708,7 @@ namespace Parser.Internal
             return new Parser.CompoundNameSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -746,7 +727,6 @@ namespace Parser.Internal
             SyntaxToken atSign,
             CompoundNameSyntaxNode functionName) : base(TokenKind.NamedFunctionHandle)
         {
-
             Slots = 2;
             this.AdjustWidth(atSign);
             _atSign = atSign;
@@ -759,7 +739,7 @@ namespace Parser.Internal
             return new Parser.NamedFunctionHandleSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -781,7 +761,6 @@ namespace Parser.Internal
             FunctionInputDescriptionSyntaxNode input,
             ExpressionSyntaxNode body) : base(TokenKind.Lambda)
         {
-
             Slots = 3;
             this.AdjustWidth(atSign);
             _atSign = atSign;
@@ -796,7 +775,7 @@ namespace Parser.Internal
             return new Parser.LambdaSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -819,7 +798,6 @@ namespace Parser.Internal
             SyntaxToken operation,
             ExpressionSyntaxNode rhs) : base(TokenKind.BinaryOperation)
         {
-
             Slots = 3;
             this.AdjustWidth(lhs);
             _lhs = lhs;
@@ -834,7 +812,7 @@ namespace Parser.Internal
             return new Parser.BinaryOperationExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -853,7 +831,6 @@ namespace Parser.Internal
         internal IdentifierNameSyntaxNode(
             SyntaxToken name) : base(TokenKind.IdentifierName)
         {
-
             Slots = 1;
             this.AdjustWidth(name);
             _name = name;
@@ -864,7 +841,7 @@ namespace Parser.Internal
             return new Parser.IdentifierNameSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -881,7 +858,6 @@ namespace Parser.Internal
         internal NumberLiteralSyntaxNode(
             SyntaxToken number) : base(TokenKind.NumberLiteralExpression)
         {
-
             Slots = 1;
             this.AdjustWidth(number);
             _number = number;
@@ -892,7 +868,7 @@ namespace Parser.Internal
             return new Parser.NumberLiteralSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -909,7 +885,6 @@ namespace Parser.Internal
         internal StringLiteralSyntaxNode(
             SyntaxToken stringToken) : base(TokenKind.StringLiteralExpression)
         {
-
             Slots = 1;
             this.AdjustWidth(stringToken);
             _stringToken = stringToken;
@@ -920,7 +895,7 @@ namespace Parser.Internal
             return new Parser.StringLiteralSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -937,7 +912,6 @@ namespace Parser.Internal
         internal DoubleQuotedStringLiteralSyntaxNode(
             SyntaxToken stringToken) : base(TokenKind.DoubleQuotedStringLiteralExpression)
         {
-
             Slots = 1;
             this.AdjustWidth(stringToken);
             _stringToken = stringToken;
@@ -948,7 +922,7 @@ namespace Parser.Internal
             return new Parser.DoubleQuotedStringLiteralSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -965,7 +939,6 @@ namespace Parser.Internal
         internal UnquotedStringLiteralSyntaxNode(
             SyntaxToken stringToken) : base(TokenKind.UnquotedStringLiteralExpression)
         {
-
             Slots = 1;
             this.AdjustWidth(stringToken);
             _stringToken = stringToken;
@@ -976,7 +949,7 @@ namespace Parser.Internal
             return new Parser.UnquotedStringLiteralSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -997,7 +970,6 @@ namespace Parser.Internal
             SyntaxList nodes,
             SyntaxToken closingSquareBracket) : base(TokenKind.ArrayLiteralExpression)
         {
-
             Slots = 3;
             this.AdjustWidth(openingSquareBracket);
             _openingSquareBracket = openingSquareBracket;
@@ -1012,7 +984,7 @@ namespace Parser.Internal
             return new Parser.ArrayLiteralExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1035,7 +1007,6 @@ namespace Parser.Internal
             SyntaxList nodes,
             SyntaxToken closingBrace) : base(TokenKind.CellArrayLiteralExpression)
         {
-
             Slots = 3;
             this.AdjustWidth(openingBrace);
             _openingBrace = openingBrace;
@@ -1050,7 +1021,7 @@ namespace Parser.Internal
             return new Parser.CellArrayLiteralExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1073,7 +1044,6 @@ namespace Parser.Internal
             ExpressionSyntaxNode expression,
             SyntaxToken closingBracket) : base(TokenKind.ParenthesizedExpression)
         {
-
             Slots = 3;
             this.AdjustWidth(openingBracket);
             _openingBracket = openingBracket;
@@ -1088,7 +1058,7 @@ namespace Parser.Internal
             return new Parser.ParenthesizedExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1113,7 +1083,6 @@ namespace Parser.Internal
             SyntaxList nodes,
             SyntaxToken closingBrace) : base(TokenKind.CellArrayElementAccess)
         {
-
             Slots = 4;
             this.AdjustWidth(expression);
             _expression = expression;
@@ -1130,7 +1099,7 @@ namespace Parser.Internal
             return new Parser.CellArrayElementAccessExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1156,7 +1125,6 @@ namespace Parser.Internal
             SyntaxList nodes,
             SyntaxToken closingBracket) : base(TokenKind.FunctionCall)
         {
-
             Slots = 4;
             this.AdjustWidth(functionName);
             _functionName = functionName;
@@ -1173,7 +1141,7 @@ namespace Parser.Internal
             return new Parser.FunctionCallExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1197,7 +1165,6 @@ namespace Parser.Internal
             SyntaxToken dot,
             SyntaxNode rightOperand) : base(TokenKind.MemberAccess)
         {
-
             Slots = 3;
             this.AdjustWidth(leftOperand);
             _leftOperand = leftOperand;
@@ -1212,7 +1179,7 @@ namespace Parser.Internal
             return new Parser.MemberAccessSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1233,7 +1200,6 @@ namespace Parser.Internal
             ExpressionSyntaxNode operand,
             SyntaxToken operation) : base(TokenKind.UnaryPostfixOperationExpression)
         {
-
             Slots = 2;
             this.AdjustWidth(operand);
             _operand = operand;
@@ -1246,7 +1212,7 @@ namespace Parser.Internal
             return new Parser.UnaryPostixOperationExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1268,7 +1234,6 @@ namespace Parser.Internal
             ExpressionSyntaxNode expression,
             SyntaxToken closingBracket) : base(TokenKind.IndirectMemberAccess)
         {
-
             Slots = 3;
             this.AdjustWidth(openingBracket);
             _openingBracket = openingBracket;
@@ -1283,7 +1248,7 @@ namespace Parser.Internal
             return new Parser.IndirectMemberAccessSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1304,7 +1269,6 @@ namespace Parser.Internal
             IdentifierNameSyntaxNode commandName,
             SyntaxList<UnquotedStringLiteralSyntaxNode> arguments) : base(TokenKind.Command)
         {
-
             Slots = 2;
             this.AdjustWidth(commandName);
             _commandName = commandName;
@@ -1317,7 +1281,7 @@ namespace Parser.Internal
             return new Parser.CommandExpressionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1339,7 +1303,6 @@ namespace Parser.Internal
             SyntaxToken atSign,
             ExpressionSyntaxNode baseClassNameAndArguments) : base(TokenKind.ClassInvokation)
         {
-
             Slots = 3;
             this.AdjustWidth(methodName);
             _methodName = methodName;
@@ -1354,7 +1317,7 @@ namespace Parser.Internal
             return new Parser.BaseClassInvokationSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1375,7 +1338,6 @@ namespace Parser.Internal
             SyntaxToken assignmentSign,
             ExpressionSyntaxNode value) : base(TokenKind.AttributeAssignment)
         {
-
             Slots = 2;
             this.AdjustWidth(assignmentSign);
             _assignmentSign = assignmentSign;
@@ -1388,7 +1350,7 @@ namespace Parser.Internal
             return new Parser.AttributeAssignmentSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1402,13 +1364,12 @@ namespace Parser.Internal
     internal class AttributeSyntaxNode : SyntaxNode
     {
         internal readonly IdentifierNameSyntaxNode _name;
-        internal readonly AttributeAssignmentSyntaxNode _assignment;
+        internal readonly AttributeAssignmentSyntaxNode? _assignment;
 
         internal AttributeSyntaxNode(
             IdentifierNameSyntaxNode name,
-            AttributeAssignmentSyntaxNode assignment) : base(TokenKind.Attribute)
+            AttributeAssignmentSyntaxNode? assignment) : base(TokenKind.Attribute)
         {
-
             Slots = 2;
             this.AdjustWidth(name);
             _name = name;
@@ -1421,7 +1382,7 @@ namespace Parser.Internal
             return new Parser.AttributeSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1443,7 +1404,6 @@ namespace Parser.Internal
             SyntaxList nodes,
             SyntaxToken closingBracket) : base(TokenKind.AttributeList)
         {
-
             Slots = 3;
             this.AdjustWidth(openingBracket);
             _openingBracket = openingBracket;
@@ -1458,7 +1418,7 @@ namespace Parser.Internal
             return new Parser.AttributeListSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1473,23 +1433,22 @@ namespace Parser.Internal
     internal class MethodDefinitionSyntaxNode : MethodDeclarationSyntaxNode
     {
         internal readonly SyntaxToken _functionKeyword;
-        internal readonly FunctionOutputDescriptionSyntaxNode _outputDescription;
+        internal readonly FunctionOutputDescriptionSyntaxNode? _outputDescription;
         internal readonly CompoundNameSyntaxNode _name;
-        internal readonly FunctionInputDescriptionSyntaxNode _inputDescription;
+        internal readonly FunctionInputDescriptionSyntaxNode? _inputDescription;
         internal readonly SyntaxList<SyntaxToken> _commas;
         internal readonly SyntaxList _body;
-        internal readonly SyntaxToken _endKeyword;
+        internal readonly EndKeywordSyntaxNode? _endKeyword;
 
         internal MethodDefinitionSyntaxNode(
             SyntaxToken functionKeyword,
-            FunctionOutputDescriptionSyntaxNode outputDescription,
+            FunctionOutputDescriptionSyntaxNode? outputDescription,
             CompoundNameSyntaxNode name,
-            FunctionInputDescriptionSyntaxNode inputDescription,
+            FunctionInputDescriptionSyntaxNode? inputDescription,
             SyntaxList<SyntaxToken> commas,
             SyntaxList body,
-            SyntaxToken endKeyword) : base(TokenKind.MethodDefinition)
+            EndKeywordSyntaxNode? endKeyword) : base(TokenKind.MethodDefinition)
         {
-
             Slots = 7;
             this.AdjustWidth(functionKeyword);
             _functionKeyword = functionKeyword;
@@ -1512,7 +1471,7 @@ namespace Parser.Internal
             return new Parser.MethodDefinitionSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1530,16 +1489,15 @@ namespace Parser.Internal
 
     internal class AbstractMethodDeclarationSyntaxNode : MethodDeclarationSyntaxNode
     {
-        internal readonly FunctionOutputDescriptionSyntaxNode _outputDescription;
+        internal readonly FunctionOutputDescriptionSyntaxNode? _outputDescription;
         internal readonly CompoundNameSyntaxNode _name;
-        internal readonly FunctionInputDescriptionSyntaxNode _inputDescription;
+        internal readonly FunctionInputDescriptionSyntaxNode? _inputDescription;
 
         internal AbstractMethodDeclarationSyntaxNode(
-            FunctionOutputDescriptionSyntaxNode outputDescription,
+            FunctionOutputDescriptionSyntaxNode? outputDescription,
             CompoundNameSyntaxNode name,
-            FunctionInputDescriptionSyntaxNode inputDescription) : base(TokenKind.AbstractMethodDeclaration)
+            FunctionInputDescriptionSyntaxNode? inputDescription) : base(TokenKind.AbstractMethodDeclaration)
         {
-
             Slots = 3;
             this.AdjustWidth(outputDescription);
             _outputDescription = outputDescription;
@@ -1554,7 +1512,7 @@ namespace Parser.Internal
             return new Parser.AbstractMethodDeclarationSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1569,17 +1527,16 @@ namespace Parser.Internal
     internal class MethodsListSyntaxNode : SyntaxNode
     {
         internal readonly SyntaxToken _methodsKeyword;
-        internal readonly AttributeListSyntaxNode _attributes;
+        internal readonly AttributeListSyntaxNode? _attributes;
         internal readonly SyntaxList _methods;
         internal readonly SyntaxToken _endKeyword;
 
         internal MethodsListSyntaxNode(
             SyntaxToken methodsKeyword,
-            AttributeListSyntaxNode attributes,
+            AttributeListSyntaxNode? attributes,
             SyntaxList methods,
             SyntaxToken endKeyword) : base(TokenKind.MethodsList)
         {
-
             Slots = 4;
             this.AdjustWidth(methodsKeyword);
             _methodsKeyword = methodsKeyword;
@@ -1596,7 +1553,7 @@ namespace Parser.Internal
             return new Parser.MethodsListSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1612,17 +1569,16 @@ namespace Parser.Internal
     internal class PropertiesListSyntaxNode : SyntaxNode
     {
         internal readonly SyntaxToken _propertiesKeyword;
-        internal readonly AttributeListSyntaxNode _attributes;
+        internal readonly AttributeListSyntaxNode? _attributes;
         internal readonly SyntaxList _properties;
         internal readonly SyntaxToken _endKeyword;
 
         internal PropertiesListSyntaxNode(
             SyntaxToken propertiesKeyword,
-            AttributeListSyntaxNode attributes,
+            AttributeListSyntaxNode? attributes,
             SyntaxList properties,
             SyntaxToken endKeyword) : base(TokenKind.PropertiesList)
         {
-
             Slots = 4;
             this.AdjustWidth(propertiesKeyword);
             _propertiesKeyword = propertiesKeyword;
@@ -1639,7 +1595,7 @@ namespace Parser.Internal
             return new Parser.PropertiesListSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1661,7 +1617,6 @@ namespace Parser.Internal
             SyntaxToken lessSign,
             SyntaxList baseClasses) : base(TokenKind.BaseClassList)
         {
-
             Slots = 2;
             this.AdjustWidth(lessSign);
             _lessSign = lessSign;
@@ -1674,7 +1629,7 @@ namespace Parser.Internal
             return new Parser.BaseClassListSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1688,21 +1643,20 @@ namespace Parser.Internal
     internal class ClassDeclarationSyntaxNode : StatementSyntaxNode
     {
         internal readonly SyntaxToken _classdefKeyword;
-        internal readonly AttributeListSyntaxNode _attributes;
+        internal readonly AttributeListSyntaxNode? _attributes;
         internal readonly IdentifierNameSyntaxNode _className;
-        internal readonly BaseClassListSyntaxNode _baseClassList;
+        internal readonly BaseClassListSyntaxNode? _baseClassList;
         internal readonly SyntaxList _nodes;
         internal readonly SyntaxToken _endKeyword;
 
         internal ClassDeclarationSyntaxNode(
             SyntaxToken classdefKeyword,
-            AttributeListSyntaxNode attributes,
+            AttributeListSyntaxNode? attributes,
             IdentifierNameSyntaxNode className,
-            BaseClassListSyntaxNode baseClassList,
+            BaseClassListSyntaxNode? baseClassList,
             SyntaxList nodes,
             SyntaxToken endKeyword) : base(TokenKind.ClassDeclaration)
         {
-
             Slots = 6;
             this.AdjustWidth(classdefKeyword);
             _classdefKeyword = classdefKeyword;
@@ -1723,7 +1677,7 @@ namespace Parser.Internal
             return new Parser.ClassDeclarationSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1749,7 +1703,6 @@ namespace Parser.Internal
             SyntaxList values,
             SyntaxToken closingBracket) : base(TokenKind.EnumerationItemValue)
         {
-
             Slots = 3;
             this.AdjustWidth(openingBracket);
             _openingBracket = openingBracket;
@@ -1764,7 +1717,7 @@ namespace Parser.Internal
             return new Parser.EnumerationItemValueSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1779,15 +1732,14 @@ namespace Parser.Internal
     internal class EnumerationItemSyntaxNode : SyntaxNode
     {
         internal readonly IdentifierNameSyntaxNode _name;
-        internal readonly EnumerationItemValueSyntaxNode _values;
+        internal readonly EnumerationItemValueSyntaxNode? _values;
         internal readonly SyntaxList<SyntaxToken> _commas;
 
         internal EnumerationItemSyntaxNode(
             IdentifierNameSyntaxNode name,
-            EnumerationItemValueSyntaxNode values,
+            EnumerationItemValueSyntaxNode? values,
             SyntaxList<SyntaxToken> commas) : base(TokenKind.EnumerationItem)
         {
-
             Slots = 3;
             this.AdjustWidth(name);
             _name = name;
@@ -1802,7 +1754,7 @@ namespace Parser.Internal
             return new Parser.EnumerationItemSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1817,17 +1769,16 @@ namespace Parser.Internal
     internal class EnumerationListSyntaxNode : SyntaxNode
     {
         internal readonly SyntaxToken _enumerationKeyword;
-        internal readonly AttributeListSyntaxNode _attributes;
+        internal readonly AttributeListSyntaxNode? _attributes;
         internal readonly SyntaxList<EnumerationItemSyntaxNode> _items;
         internal readonly SyntaxToken _endKeyword;
 
         internal EnumerationListSyntaxNode(
             SyntaxToken enumerationKeyword,
-            AttributeListSyntaxNode attributes,
+            AttributeListSyntaxNode? attributes,
             SyntaxList<EnumerationItemSyntaxNode> items,
             SyntaxToken endKeyword) : base(TokenKind.EnumerationList)
         {
-
             Slots = 4;
             this.AdjustWidth(enumerationKeyword);
             _enumerationKeyword = enumerationKeyword;
@@ -1844,7 +1795,7 @@ namespace Parser.Internal
             return new Parser.EnumerationListSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1860,17 +1811,16 @@ namespace Parser.Internal
     internal class EventsListSyntaxNode : SyntaxNode
     {
         internal readonly SyntaxToken _eventsKeyword;
-        internal readonly AttributeListSyntaxNode _attributes;
+        internal readonly AttributeListSyntaxNode? _attributes;
         internal readonly SyntaxList _events;
         internal readonly SyntaxToken _endKeyword;
 
         internal EventsListSyntaxNode(
             SyntaxToken eventsKeyword,
-            AttributeListSyntaxNode attributes,
+            AttributeListSyntaxNode? attributes,
             SyntaxList events,
             SyntaxToken endKeyword) : base(TokenKind.EventsList)
         {
-
             Slots = 4;
             this.AdjustWidth(eventsKeyword);
             _eventsKeyword = eventsKeyword;
@@ -1887,7 +1837,7 @@ namespace Parser.Internal
             return new Parser.EventsListSyntaxNode(parent, this, position);
         }
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             switch (i)
             {
@@ -1899,4 +1849,31 @@ namespace Parser.Internal
             }
         }
     }
+
+    internal class EndKeywordSyntaxNode : SyntaxNode
+    {
+        internal readonly SyntaxToken _endKeyword;
+
+        internal EndKeywordSyntaxNode(
+            SyntaxToken endKeyword) : base(TokenKind.EndKeyword)
+        {
+            Slots = 1;
+            this.AdjustWidth(endKeyword);
+            _endKeyword = endKeyword;
+        }
+
+        internal override Parser.SyntaxNode CreateRed(Parser.SyntaxNode parent, int position)
+        {
+            return new Parser.EndKeywordSyntaxNode(parent, this, position);
+        }
+
+        public override GreenNode? GetSlot(int i)
+        {
+            switch (i)
+            {
+                case 0: return _endKeyword;
+                default: return null;
+            }
+        }
+    }
 }
diff --git a/Parser/Internal/SyntaxNode.cs b/Parser/Internal/SyntaxNode.cs
index 9ddf794..2223e89 100644
--- a/Parser/Internal/SyntaxNode.cs
+++ b/Parser/Internal/SyntaxNode.cs
@@ -79,4 +79,30 @@ namespace Parser.Internal
         {
         }
     }
+
+    internal class RootSyntaxNode : SyntaxNode
+    {
+        internal readonly FileSyntaxNode _file;
+
+        public RootSyntaxNode(FileSyntaxNode file) : base(TokenKind.Root)
+        {
+            Slots = 1;
+            this.AdjustWidth(file);
+            _file = file;
+        }
+
+        public override GreenNode? GetSlot(int i)
+        {
+            switch (i)
+            {
+                case 0: return _file;
+                default: return null;
+            }
+        }
+
+        internal override Parser.SyntaxNode CreateRed(Parser.SyntaxNode parent, int position)
+        {
+            return new Parser.RootSyntaxNode(this, position);
+        }
+    }
 }
diff --git a/Parser/Internal/SyntaxToken.cs b/Parser/Internal/SyntaxToken.cs
index b230044..3a79599 100644
--- a/Parser/Internal/SyntaxToken.cs
+++ b/Parser/Internal/SyntaxToken.cs
@@ -7,7 +7,7 @@ namespace Parser.Internal
 {
     internal abstract class SyntaxToken : GreenNode
     {
-        public TextSpan Span { get; }
+        internal static IReadOnlyList<SyntaxTrivia> s_EmptySyntaxTriviaList = new List<SyntaxTrivia>();
 
         internal class SyntaxTokenWithTrivia : SyntaxToken
         {
@@ -197,13 +197,15 @@ namespace Parser.Internal
         protected SyntaxToken(TokenKind kind) : base(kind)
         {
         }
+
+        internal static SyntaxToken NoneToken => new MissingTokenWithTrivia(TokenKind.None, s_EmptySyntaxTriviaList, s_EmptySyntaxTriviaList);
         
         public virtual int Width => Text.Length;
 
-        public override IReadOnlyList<SyntaxTrivia> LeadingTriviaCore => new List<SyntaxTrivia>();
-        public override IReadOnlyList<SyntaxTrivia> TrailingTriviaCore => new List<SyntaxTrivia>();
+        public override IReadOnlyList<SyntaxTrivia> LeadingTriviaCore => s_EmptySyntaxTriviaList;
+        public override IReadOnlyList<SyntaxTrivia> TrailingTriviaCore => s_EmptySyntaxTriviaList;
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             throw new System.InvalidOperationException();
         }
diff --git a/Parser/Internal/SyntaxTrivia.cs b/Parser/Internal/SyntaxTrivia.cs
index 3d74c34..0ab0377 100644
--- a/Parser/Internal/SyntaxTrivia.cs
+++ b/Parser/Internal/SyntaxTrivia.cs
@@ -17,7 +17,7 @@ namespace Parser.Internal
         public override string Text => _text;
         public int Width => _text.Length;
 
-        public override GreenNode GetSlot(int i)
+        public override GreenNode? GetSlot(int i)
         {
             throw new System.NotImplementedException();
         }
diff --git a/Parser/Internal/TokenFactory.cs b/Parser/Internal/TokenFactory.cs
index 221d734..1281663 100644
--- a/Parser/Internal/TokenFactory.cs
+++ b/Parser/Internal/TokenFactory.cs
@@ -51,10 +51,10 @@ namespace Parser.Internal
 
         public static SyntaxToken CreateMissing(
             TokenKind kind,
-            IReadOnlyList<SyntaxTrivia> leadingTrivia,
-            IReadOnlyList<SyntaxTrivia> trailingTrivia)
+            IReadOnlyList<SyntaxTrivia>? leadingTrivia,
+            IReadOnlyList<SyntaxTrivia>? trailingTrivia)
         {
-            return new SyntaxToken.MissingTokenWithTrivia(kind, leadingTrivia, trailingTrivia);
+            return new SyntaxToken.MissingTokenWithTrivia(kind, leadingTrivia ?? SyntaxToken.s_EmptySyntaxTriviaList, trailingTrivia ?? SyntaxToken.s_EmptySyntaxTriviaList);
         }
     }
 }
\ No newline at end of file
diff --git a/Parser/MParser.cs b/Parser/MParser.cs
index 8a3d7a1..e47a1a8 100644
--- a/Parser/MParser.cs
+++ b/Parser/MParser.cs
@@ -20,23 +20,24 @@ namespace Parser
             var lexerDiagnostics = lexer.Diagnostics;
             var tokens = lexer.ParseAll();
             var parser = new Internal.MParserGreen(tokens, new Internal.SyntaxFactory());
-            var green = parser.ParseFile();
+            var green = parser.ParseRoot();
             var parserDiagnostics = parser.Diagnostics;
             var totalDiagnostics = new DiagnosticsBag(lexerDiagnostics.Concat(parserDiagnostics));
-            var root = new FileSyntaxNode(null, green, 0);
+            var root = new RootSyntaxNode(green, 0);
             return new SyntaxTree(root, totalDiagnostics);
         }
     }
 
     public class SyntaxTree
     {
-        public SyntaxTree(FileSyntaxNode root, DiagnosticsBag diagnostics)
+        public SyntaxTree(RootSyntaxNode nullRoot, DiagnosticsBag diagnostics)
         {
-            Root = root ?? throw new ArgumentNullException(nameof(root));
+            NullRoot = nullRoot ?? throw new ArgumentNullException(nameof(nullRoot));
             Diagnostics = diagnostics ?? throw new ArgumentNullException(nameof(diagnostics));
         }
 
-        public FileSyntaxNode Root { get; }
+        public RootSyntaxNode NullRoot { get; }
+        public FileSyntaxNode Root => NullRoot.File;
         public DiagnosticsBag Diagnostics { get; }
     }
 
diff --git a/Parser/Parser.csproj b/Parser/Parser.csproj
index 2e5ff7c..180cb57 100644
--- a/Parser/Parser.csproj
+++ b/Parser/Parser.csproj
@@ -1,6 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <LangVersion>8.0</LangVersion>
+    <NullableReferenceTypes>true</NullableReferenceTypes>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
diff --git a/Parser/Position.cs b/Parser/Position.cs
index 56a71a5..e4ec6fe 100644
--- a/Parser/Position.cs
+++ b/Parser/Position.cs
@@ -2,7 +2,7 @@
 {
     public struct Position
     {
-        public string FileName { get; set; }
+        public string? FileName { get; set; }
         public int Line { get; set; }
         public int Column { get; set; }
         public int Offset { get; set; }
diff --git a/Parser/SyntaxNode.Generated.cs b/Parser/SyntaxNode.Generated.cs
index a621d93..bb59e96 100644
--- a/Parser/SyntaxNode.Generated.cs
+++ b/Parser/SyntaxNode.Generated.cs
@@ -2,7 +2,7 @@ namespace Parser
 {
     public class FileSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _statementList;
+        private SyntaxNode? _statementList;
 
         internal FileSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -17,19 +17,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._statementList, 0);
+                var red = this.GetRed(ref this._statementList!, 0);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("statementList cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _statementList, 0);
+                case 0: return GetRed(ref _statementList!, 0);
                 default: return null;
             }
         }
@@ -43,10 +43,11 @@ namespace Parser
 
     public class FunctionDeclarationSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _outputDescription;
-        private SyntaxNode _inputDescription;
-        private SyntaxNode _commas;
-        private SyntaxNode _body;
+        private SyntaxNode? _outputDescription;
+        private SyntaxNode? _inputDescription;
+        private SyntaxNode? _commas;
+        private SyntaxNode? _body;
+        private SyntaxNode? _endKeyword;
 
         internal FunctionDeclarationSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -62,12 +63,7 @@ namespace Parser
             get { return new SyntaxToken(this, ((Parser.Internal.FunctionDeclarationSyntaxNode)_green)._name, this.GetChildPosition(2)); }
         }
 
-        public SyntaxToken EndKeyword
-        {
-            get { return new SyntaxToken(this, ((Parser.Internal.FunctionDeclarationSyntaxNode)_green)._endKeyword, this.GetChildPosition(6)); }
-        }
-
-        public FunctionOutputDescriptionSyntaxNode OutputDescription
+        public FunctionOutputDescriptionSyntaxNode? OutputDescription
         {
             get
             {
@@ -79,7 +75,7 @@ namespace Parser
             }
         }
 
-        public FunctionInputDescriptionSyntaxNode InputDescription
+        public FunctionInputDescriptionSyntaxNode? InputDescription
         {
             get
             {
@@ -95,11 +91,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._commas, 4);
+                var red = this.GetRed(ref this._commas!, 4);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("commas cannot be null");
             }
         }
 
@@ -107,22 +103,35 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 5);
+                var red = this.GetRed(ref this._body!, 5);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        public EndKeywordSyntaxNode? EndKeyword
+        {
+            get
+            {
+                var red = this.GetRed(ref this._endKeyword, 6);
+                if (red != null)
+                    return (EndKeywordSyntaxNode)red;
+
+                return default(EndKeywordSyntaxNode);
+            }
+        }
+
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 1: return GetRed(ref _outputDescription, 1);
                 case 3: return GetRed(ref _inputDescription, 3);
-                case 4: return GetRed(ref _commas, 4);
-                case 5: return GetRed(ref _body, 5);
+                case 4: return GetRed(ref _commas!, 4);
+                case 5: return GetRed(ref _body!, 5);
+                case 6: return GetRed(ref _endKeyword, 6);
                 default: return null;
             }
         }
@@ -136,7 +145,7 @@ namespace Parser
 
     public class FunctionOutputDescriptionSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _outputList;
+        private SyntaxNode? _outputList;
 
         internal FunctionOutputDescriptionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -151,19 +160,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._outputList, 0);
+                var red = this.GetRed(ref this._outputList!, 0);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("outputList cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _outputList, 0);
+                case 0: return GetRed(ref _outputList!, 0);
                 default: return null;
             }
         }
@@ -177,7 +186,7 @@ namespace Parser
 
     public class FunctionInputDescriptionSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _parameterList;
+        private SyntaxNode? _parameterList;
 
         internal FunctionInputDescriptionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -197,19 +206,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._parameterList, 1);
+                var red = this.GetRed(ref this._parameterList!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("parameterList cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _parameterList, 1);
+                case 1: return GetRed(ref _parameterList!, 1);
                 default: return null;
             }
         }
@@ -223,9 +232,9 @@ namespace Parser
 
     public class SwitchStatementSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _switchExpression;
-        private SyntaxNode _optionalCommas;
-        private SyntaxNode _cases;
+        private SyntaxNode? _switchExpression;
+        private SyntaxNode? _optionalCommas;
+        private SyntaxNode? _cases;
 
         internal SwitchStatementSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -245,11 +254,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._switchExpression, 1);
+                var red = this.GetRed(ref this._switchExpression!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("switchExpression cannot be null");
             }
         }
 
@@ -257,11 +266,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._optionalCommas, 2);
+                var red = this.GetRed(ref this._optionalCommas!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("optionalCommas cannot be null");
             }
         }
 
@@ -269,21 +278,21 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._cases, 3);
+                var red = this.GetRed(ref this._cases!, 3);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("cases cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _switchExpression, 1);
-                case 2: return GetRed(ref _optionalCommas, 2);
-                case 3: return GetRed(ref _cases, 3);
+                case 1: return GetRed(ref _switchExpression!, 1);
+                case 2: return GetRed(ref _optionalCommas!, 2);
+                case 3: return GetRed(ref _cases!, 3);
                 default: return null;
             }
         }
@@ -297,9 +306,9 @@ namespace Parser
 
     public class SwitchCaseSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _caseIdentifier;
-        private SyntaxNode _optionalCommas;
-        private SyntaxNode _body;
+        private SyntaxNode? _caseIdentifier;
+        private SyntaxNode? _optionalCommas;
+        private SyntaxNode? _body;
 
         internal SwitchCaseSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -314,11 +323,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._caseIdentifier, 1);
+                var red = this.GetRed(ref this._caseIdentifier!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("caseIdentifier cannot be null");
             }
         }
 
@@ -326,11 +335,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._optionalCommas, 2);
+                var red = this.GetRed(ref this._optionalCommas!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("optionalCommas cannot be null");
             }
         }
 
@@ -338,21 +347,21 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 3);
+                var red = this.GetRed(ref this._body!, 3);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _caseIdentifier, 1);
-                case 2: return GetRed(ref _optionalCommas, 2);
-                case 3: return GetRed(ref _body, 3);
+                case 1: return GetRed(ref _caseIdentifier!, 1);
+                case 2: return GetRed(ref _optionalCommas!, 2);
+                case 3: return GetRed(ref _body!, 3);
                 default: return null;
             }
         }
@@ -366,9 +375,9 @@ namespace Parser
 
     public class WhileStatementSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _condition;
-        private SyntaxNode _optionalCommas;
-        private SyntaxNode _body;
+        private SyntaxNode? _condition;
+        private SyntaxNode? _optionalCommas;
+        private SyntaxNode? _body;
 
         internal WhileStatementSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -388,11 +397,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._condition, 1);
+                var red = this.GetRed(ref this._condition!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("condition cannot be null");
             }
         }
 
@@ -400,11 +409,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._optionalCommas, 2);
+                var red = this.GetRed(ref this._optionalCommas!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("optionalCommas cannot be null");
             }
         }
 
@@ -412,21 +421,21 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 3);
+                var red = this.GetRed(ref this._body!, 3);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _condition, 1);
-                case 2: return GetRed(ref _optionalCommas, 2);
-                case 3: return GetRed(ref _body, 3);
+                case 1: return GetRed(ref _condition!, 1);
+                case 2: return GetRed(ref _optionalCommas!, 2);
+                case 3: return GetRed(ref _body!, 3);
                 default: return null;
             }
         }
@@ -440,9 +449,9 @@ namespace Parser
 
     public class ElseifClause : SyntaxNode
     {
-        private SyntaxNode _condition;
-        private SyntaxNode _optionalCommas;
-        private SyntaxNode _body;
+        private SyntaxNode? _condition;
+        private SyntaxNode? _optionalCommas;
+        private SyntaxNode? _body;
 
         internal ElseifClause(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -457,11 +466,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._condition, 1);
+                var red = this.GetRed(ref this._condition!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("condition cannot be null");
             }
         }
 
@@ -469,11 +478,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._optionalCommas, 2);
+                var red = this.GetRed(ref this._optionalCommas!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("optionalCommas cannot be null");
             }
         }
 
@@ -481,21 +490,21 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 3);
+                var red = this.GetRed(ref this._body!, 3);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _condition, 1);
-                case 2: return GetRed(ref _optionalCommas, 2);
-                case 3: return GetRed(ref _body, 3);
+                case 1: return GetRed(ref _condition!, 1);
+                case 2: return GetRed(ref _optionalCommas!, 2);
+                case 3: return GetRed(ref _body!, 3);
                 default: return null;
             }
         }
@@ -509,7 +518,7 @@ namespace Parser
 
     public class ElseClause : SyntaxNode
     {
-        private SyntaxNode _body;
+        private SyntaxNode? _body;
 
         internal ElseClause(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -524,19 +533,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 1);
+                var red = this.GetRed(ref this._body!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _body, 1);
+                case 1: return GetRed(ref _body!, 1);
                 default: return null;
             }
         }
@@ -550,11 +559,11 @@ namespace Parser
 
     public class IfStatementSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _condition;
-        private SyntaxNode _optionalCommas;
-        private SyntaxNode _body;
-        private SyntaxNode _elseifClauses;
-        private SyntaxNode _elseClause;
+        private SyntaxNode? _condition;
+        private SyntaxNode? _optionalCommas;
+        private SyntaxNode? _body;
+        private SyntaxNode? _elseifClauses;
+        private SyntaxNode? _elseClause;
 
         internal IfStatementSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -574,11 +583,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._condition, 1);
+                var red = this.GetRed(ref this._condition!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("condition cannot be null");
             }
         }
 
@@ -586,11 +595,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._optionalCommas, 2);
+                var red = this.GetRed(ref this._optionalCommas!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("optionalCommas cannot be null");
             }
         }
 
@@ -598,11 +607,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 3);
+                var red = this.GetRed(ref this._body!, 3);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
@@ -610,15 +619,15 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._elseifClauses, 4);
+                var red = this.GetRed(ref this._elseifClauses!, 4);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("elseifClauses cannot be null");
             }
         }
 
-        public ElseClause ElseClause
+        public ElseClause? ElseClause
         {
             get
             {
@@ -630,14 +639,14 @@ namespace Parser
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _condition, 1);
-                case 2: return GetRed(ref _optionalCommas, 2);
-                case 3: return GetRed(ref _body, 3);
-                case 4: return GetRed(ref _elseifClauses, 4);
+                case 1: return GetRed(ref _condition!, 1);
+                case 2: return GetRed(ref _optionalCommas!, 2);
+                case 3: return GetRed(ref _body!, 3);
+                case 4: return GetRed(ref _elseifClauses!, 4);
                 case 5: return GetRed(ref _elseClause, 5);
                 default: return null;
             }
@@ -652,9 +661,9 @@ namespace Parser
 
     public class ForStatementSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _assignment;
-        private SyntaxNode _optionalCommas;
-        private SyntaxNode _body;
+        private SyntaxNode? _assignment;
+        private SyntaxNode? _optionalCommas;
+        private SyntaxNode? _body;
 
         internal ForStatementSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -674,11 +683,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._assignment, 1);
+                var red = this.GetRed(ref this._assignment!, 1);
                 if (red != null)
                     return (AssignmentExpressionSyntaxNode)red;
 
-                return default(AssignmentExpressionSyntaxNode);
+                throw new System.Exception("assignment cannot be null");
             }
         }
 
@@ -686,11 +695,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._optionalCommas, 2);
+                var red = this.GetRed(ref this._optionalCommas!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("optionalCommas cannot be null");
             }
         }
 
@@ -698,21 +707,21 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 3);
+                var red = this.GetRed(ref this._body!, 3);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _assignment, 1);
-                case 2: return GetRed(ref _optionalCommas, 2);
-                case 3: return GetRed(ref _body, 3);
+                case 1: return GetRed(ref _assignment!, 1);
+                case 2: return GetRed(ref _optionalCommas!, 2);
+                case 3: return GetRed(ref _body!, 3);
                 default: return null;
             }
         }
@@ -726,8 +735,8 @@ namespace Parser
 
     public class AssignmentExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _lhs;
-        private SyntaxNode _rhs;
+        private SyntaxNode? _lhs;
+        private SyntaxNode? _rhs;
 
         internal AssignmentExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -742,11 +751,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._lhs, 0);
+                var red = this.GetRed(ref this._lhs!, 0);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("lhs cannot be null");
             }
         }
 
@@ -754,20 +763,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._rhs, 2);
+                var red = this.GetRed(ref this._rhs!, 2);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("rhs cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _lhs, 0);
-                case 2: return GetRed(ref _rhs, 2);
+                case 0: return GetRed(ref _lhs!, 0);
+                case 2: return GetRed(ref _rhs!, 2);
                 default: return null;
             }
         }
@@ -781,7 +790,7 @@ namespace Parser
 
     public class CatchClauseSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _catchBody;
+        private SyntaxNode? _catchBody;
 
         internal CatchClauseSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -796,19 +805,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._catchBody, 1);
+                var red = this.GetRed(ref this._catchBody!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("catchBody cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _catchBody, 1);
+                case 1: return GetRed(ref _catchBody!, 1);
                 default: return null;
             }
         }
@@ -822,8 +831,8 @@ namespace Parser
 
     public class TryCatchStatementSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _tryBody;
-        private SyntaxNode _catchClause;
+        private SyntaxNode? _tryBody;
+        private SyntaxNode? _catchClause;
 
         internal TryCatchStatementSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -843,15 +852,15 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._tryBody, 1);
+                var red = this.GetRed(ref this._tryBody!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("tryBody cannot be null");
             }
         }
 
-        public CatchClauseSyntaxNode CatchClause
+        public CatchClauseSyntaxNode? CatchClause
         {
             get
             {
@@ -863,11 +872,11 @@ namespace Parser
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _tryBody, 1);
+                case 1: return GetRed(ref _tryBody!, 1);
                 case 2: return GetRed(ref _catchClause, 2);
                 default: return null;
             }
@@ -882,7 +891,7 @@ namespace Parser
 
     public class ExpressionStatementSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _expression;
+        private SyntaxNode? _expression;
 
         internal ExpressionStatementSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -893,19 +902,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._expression, 0);
+                var red = this.GetRed(ref this._expression!, 0);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("expression cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _expression, 0);
+                case 0: return GetRed(ref _expression!, 0);
                 default: return null;
             }
         }
@@ -930,7 +939,7 @@ namespace Parser
         }
 
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
@@ -954,7 +963,7 @@ namespace Parser
 
 
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
@@ -971,7 +980,7 @@ namespace Parser
 
     public class UnaryPrefixOperationExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _operand;
+        private SyntaxNode? _operand;
 
         internal UnaryPrefixOperationExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -986,19 +995,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._operand, 1);
+                var red = this.GetRed(ref this._operand!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("operand cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _operand, 1);
+                case 1: return GetRed(ref _operand!, 1);
                 default: return null;
             }
         }
@@ -1012,7 +1021,7 @@ namespace Parser
 
     public class CompoundNameSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _nodes;
+        private SyntaxNode? _nodes;
 
         internal CompoundNameSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1023,19 +1032,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._nodes, 0);
+                var red = this.GetRed(ref this._nodes!, 0);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("nodes cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _nodes, 0);
+                case 0: return GetRed(ref _nodes!, 0);
                 default: return null;
             }
         }
@@ -1049,7 +1058,7 @@ namespace Parser
 
     public class NamedFunctionHandleSyntaxNode : FunctionHandleSyntaxNode
     {
-        private SyntaxNode _functionName;
+        private SyntaxNode? _functionName;
 
         internal NamedFunctionHandleSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1064,19 +1073,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._functionName, 1);
+                var red = this.GetRed(ref this._functionName!, 1);
                 if (red != null)
                     return (CompoundNameSyntaxNode)red;
 
-                return default(CompoundNameSyntaxNode);
+                throw new System.Exception("functionName cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _functionName, 1);
+                case 1: return GetRed(ref _functionName!, 1);
                 default: return null;
             }
         }
@@ -1090,8 +1099,8 @@ namespace Parser
 
     public class LambdaSyntaxNode : FunctionHandleSyntaxNode
     {
-        private SyntaxNode _input;
-        private SyntaxNode _body;
+        private SyntaxNode? _input;
+        private SyntaxNode? _body;
 
         internal LambdaSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1106,11 +1115,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._input, 1);
+                var red = this.GetRed(ref this._input!, 1);
                 if (red != null)
                     return (FunctionInputDescriptionSyntaxNode)red;
 
-                return default(FunctionInputDescriptionSyntaxNode);
+                throw new System.Exception("input cannot be null");
             }
         }
 
@@ -1118,20 +1127,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 2);
+                var red = this.GetRed(ref this._body!, 2);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _input, 1);
-                case 2: return GetRed(ref _body, 2);
+                case 1: return GetRed(ref _input!, 1);
+                case 2: return GetRed(ref _body!, 2);
                 default: return null;
             }
         }
@@ -1145,8 +1154,8 @@ namespace Parser
 
     public class BinaryOperationExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _lhs;
-        private SyntaxNode _rhs;
+        private SyntaxNode? _lhs;
+        private SyntaxNode? _rhs;
 
         internal BinaryOperationExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1161,11 +1170,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._lhs, 0);
+                var red = this.GetRed(ref this._lhs!, 0);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("lhs cannot be null");
             }
         }
 
@@ -1173,20 +1182,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._rhs, 2);
+                var red = this.GetRed(ref this._rhs!, 2);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("rhs cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _lhs, 0);
-                case 2: return GetRed(ref _rhs, 2);
+                case 0: return GetRed(ref _lhs!, 0);
+                case 2: return GetRed(ref _rhs!, 2);
                 default: return null;
             }
         }
@@ -1211,7 +1220,7 @@ namespace Parser
         }
 
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
@@ -1239,7 +1248,7 @@ namespace Parser
         }
 
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
@@ -1267,7 +1276,7 @@ namespace Parser
         }
 
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
@@ -1295,7 +1304,7 @@ namespace Parser
         }
 
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
@@ -1323,7 +1332,7 @@ namespace Parser
         }
 
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
@@ -1340,7 +1349,7 @@ namespace Parser
 
     public class ArrayLiteralExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _nodes;
+        private SyntaxNode? _nodes;
 
         internal ArrayLiteralExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1360,19 +1369,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._nodes, 1);
+                var red = this.GetRed(ref this._nodes!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("nodes cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _nodes, 1);
+                case 1: return GetRed(ref _nodes!, 1);
                 default: return null;
             }
         }
@@ -1386,7 +1395,7 @@ namespace Parser
 
     public class CellArrayLiteralExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _nodes;
+        private SyntaxNode? _nodes;
 
         internal CellArrayLiteralExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1406,19 +1415,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._nodes, 1);
+                var red = this.GetRed(ref this._nodes!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("nodes cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _nodes, 1);
+                case 1: return GetRed(ref _nodes!, 1);
                 default: return null;
             }
         }
@@ -1432,7 +1441,7 @@ namespace Parser
 
     public class ParenthesizedExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _expression;
+        private SyntaxNode? _expression;
 
         internal ParenthesizedExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1452,19 +1461,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._expression, 1);
+                var red = this.GetRed(ref this._expression!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("expression cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _expression, 1);
+                case 1: return GetRed(ref _expression!, 1);
                 default: return null;
             }
         }
@@ -1478,8 +1487,8 @@ namespace Parser
 
     public class CellArrayElementAccessExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _expression;
-        private SyntaxNode _nodes;
+        private SyntaxNode? _expression;
+        private SyntaxNode? _nodes;
 
         internal CellArrayElementAccessExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1499,11 +1508,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._expression, 0);
+                var red = this.GetRed(ref this._expression!, 0);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("expression cannot be null");
             }
         }
 
@@ -1511,20 +1520,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._nodes, 2);
+                var red = this.GetRed(ref this._nodes!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("nodes cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _expression, 0);
-                case 2: return GetRed(ref _nodes, 2);
+                case 0: return GetRed(ref _expression!, 0);
+                case 2: return GetRed(ref _nodes!, 2);
                 default: return null;
             }
         }
@@ -1538,8 +1547,8 @@ namespace Parser
 
     public class FunctionCallExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _functionName;
-        private SyntaxNode _nodes;
+        private SyntaxNode? _functionName;
+        private SyntaxNode? _nodes;
 
         internal FunctionCallExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1559,11 +1568,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._functionName, 0);
+                var red = this.GetRed(ref this._functionName!, 0);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("functionName cannot be null");
             }
         }
 
@@ -1571,20 +1580,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._nodes, 2);
+                var red = this.GetRed(ref this._nodes!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("nodes cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _functionName, 0);
-                case 2: return GetRed(ref _nodes, 2);
+                case 0: return GetRed(ref _functionName!, 0);
+                case 2: return GetRed(ref _nodes!, 2);
                 default: return null;
             }
         }
@@ -1598,8 +1607,8 @@ namespace Parser
 
     public class MemberAccessSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _leftOperand;
-        private SyntaxNode _rightOperand;
+        private SyntaxNode? _leftOperand;
+        private SyntaxNode? _rightOperand;
 
         internal MemberAccessSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1614,11 +1623,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._leftOperand, 0);
+                var red = this.GetRed(ref this._leftOperand!, 0);
                 if (red != null)
                     return (SyntaxNode)red;
 
-                return default(SyntaxNode);
+                throw new System.Exception("leftOperand cannot be null");
             }
         }
 
@@ -1626,20 +1635,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._rightOperand, 2);
+                var red = this.GetRed(ref this._rightOperand!, 2);
                 if (red != null)
                     return (SyntaxNode)red;
 
-                return default(SyntaxNode);
+                throw new System.Exception("rightOperand cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _leftOperand, 0);
-                case 2: return GetRed(ref _rightOperand, 2);
+                case 0: return GetRed(ref _leftOperand!, 0);
+                case 2: return GetRed(ref _rightOperand!, 2);
                 default: return null;
             }
         }
@@ -1653,7 +1662,7 @@ namespace Parser
 
     public class UnaryPostixOperationExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _operand;
+        private SyntaxNode? _operand;
 
         internal UnaryPostixOperationExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1668,19 +1677,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._operand, 0);
+                var red = this.GetRed(ref this._operand!, 0);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("operand cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _operand, 0);
+                case 0: return GetRed(ref _operand!, 0);
                 default: return null;
             }
         }
@@ -1694,7 +1703,7 @@ namespace Parser
 
     public class IndirectMemberAccessSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _expression;
+        private SyntaxNode? _expression;
 
         internal IndirectMemberAccessSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1714,19 +1723,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._expression, 1);
+                var red = this.GetRed(ref this._expression!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("expression cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _expression, 1);
+                case 1: return GetRed(ref _expression!, 1);
                 default: return null;
             }
         }
@@ -1740,8 +1749,8 @@ namespace Parser
 
     public class CommandExpressionSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _commandName;
-        private SyntaxNode _arguments;
+        private SyntaxNode? _commandName;
+        private SyntaxNode? _arguments;
 
         internal CommandExpressionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1752,11 +1761,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._commandName, 0);
+                var red = this.GetRed(ref this._commandName!, 0);
                 if (red != null)
                     return (IdentifierNameSyntaxNode)red;
 
-                return default(IdentifierNameSyntaxNode);
+                throw new System.Exception("commandName cannot be null");
             }
         }
 
@@ -1764,20 +1773,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._arguments, 1);
+                var red = this.GetRed(ref this._arguments!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("arguments cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _commandName, 0);
-                case 1: return GetRed(ref _arguments, 1);
+                case 0: return GetRed(ref _commandName!, 0);
+                case 1: return GetRed(ref _arguments!, 1);
                 default: return null;
             }
         }
@@ -1791,8 +1800,8 @@ namespace Parser
 
     public class BaseClassInvokationSyntaxNode : ExpressionSyntaxNode
     {
-        private SyntaxNode _methodName;
-        private SyntaxNode _baseClassNameAndArguments;
+        private SyntaxNode? _methodName;
+        private SyntaxNode? _baseClassNameAndArguments;
 
         internal BaseClassInvokationSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1807,11 +1816,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._methodName, 0);
+                var red = this.GetRed(ref this._methodName!, 0);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("methodName cannot be null");
             }
         }
 
@@ -1819,20 +1828,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._baseClassNameAndArguments, 2);
+                var red = this.GetRed(ref this._baseClassNameAndArguments!, 2);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("baseClassNameAndArguments cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _methodName, 0);
-                case 2: return GetRed(ref _baseClassNameAndArguments, 2);
+                case 0: return GetRed(ref _methodName!, 0);
+                case 2: return GetRed(ref _baseClassNameAndArguments!, 2);
                 default: return null;
             }
         }
@@ -1846,7 +1855,7 @@ namespace Parser
 
     public class AttributeAssignmentSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _value;
+        private SyntaxNode? _value;
 
         internal AttributeAssignmentSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1861,19 +1870,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._value, 1);
+                var red = this.GetRed(ref this._value!, 1);
                 if (red != null)
                     return (ExpressionSyntaxNode)red;
 
-                return default(ExpressionSyntaxNode);
+                throw new System.Exception("value cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _value, 1);
+                case 1: return GetRed(ref _value!, 1);
                 default: return null;
             }
         }
@@ -1887,8 +1896,8 @@ namespace Parser
 
     public class AttributeSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _name;
-        private SyntaxNode _assignment;
+        private SyntaxNode? _name;
+        private SyntaxNode? _assignment;
 
         internal AttributeSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1899,15 +1908,15 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._name, 0);
+                var red = this.GetRed(ref this._name!, 0);
                 if (red != null)
                     return (IdentifierNameSyntaxNode)red;
 
-                return default(IdentifierNameSyntaxNode);
+                throw new System.Exception("name cannot be null");
             }
         }
 
-        public AttributeAssignmentSyntaxNode Assignment
+        public AttributeAssignmentSyntaxNode? Assignment
         {
             get
             {
@@ -1919,11 +1928,11 @@ namespace Parser
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _name, 0);
+                case 0: return GetRed(ref _name!, 0);
                 case 1: return GetRed(ref _assignment, 1);
                 default: return null;
             }
@@ -1938,7 +1947,7 @@ namespace Parser
 
     public class AttributeListSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _nodes;
+        private SyntaxNode? _nodes;
 
         internal AttributeListSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1958,19 +1967,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._nodes, 1);
+                var red = this.GetRed(ref this._nodes!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("nodes cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _nodes, 1);
+                case 1: return GetRed(ref _nodes!, 1);
                 default: return null;
             }
         }
@@ -1984,11 +1993,12 @@ namespace Parser
 
     public class MethodDefinitionSyntaxNode : MethodDeclarationSyntaxNode
     {
-        private SyntaxNode _outputDescription;
-        private SyntaxNode _name;
-        private SyntaxNode _inputDescription;
-        private SyntaxNode _commas;
-        private SyntaxNode _body;
+        private SyntaxNode? _outputDescription;
+        private SyntaxNode? _name;
+        private SyntaxNode? _inputDescription;
+        private SyntaxNode? _commas;
+        private SyntaxNode? _body;
+        private SyntaxNode? _endKeyword;
 
         internal MethodDefinitionSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -1999,12 +2009,7 @@ namespace Parser
             get { return new SyntaxToken(this, ((Parser.Internal.MethodDefinitionSyntaxNode)_green)._functionKeyword, this.GetChildPosition(0)); }
         }
 
-        public SyntaxToken EndKeyword
-        {
-            get { return new SyntaxToken(this, ((Parser.Internal.MethodDefinitionSyntaxNode)_green)._endKeyword, this.GetChildPosition(6)); }
-        }
-
-        public FunctionOutputDescriptionSyntaxNode OutputDescription
+        public FunctionOutputDescriptionSyntaxNode? OutputDescription
         {
             get
             {
@@ -2020,15 +2025,15 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._name, 2);
+                var red = this.GetRed(ref this._name!, 2);
                 if (red != null)
                     return (CompoundNameSyntaxNode)red;
 
-                return default(CompoundNameSyntaxNode);
+                throw new System.Exception("name cannot be null");
             }
         }
 
-        public FunctionInputDescriptionSyntaxNode InputDescription
+        public FunctionInputDescriptionSyntaxNode? InputDescription
         {
             get
             {
@@ -2044,11 +2049,11 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._commas, 4);
+                var red = this.GetRed(ref this._commas!, 4);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("commas cannot be null");
             }
         }
 
@@ -2056,23 +2061,36 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._body, 5);
+                var red = this.GetRed(ref this._body!, 5);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("body cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        public EndKeywordSyntaxNode? EndKeyword
+        {
+            get
+            {
+                var red = this.GetRed(ref this._endKeyword, 6);
+                if (red != null)
+                    return (EndKeywordSyntaxNode)red;
+
+                return default(EndKeywordSyntaxNode);
+            }
+        }
+
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 1: return GetRed(ref _outputDescription, 1);
-                case 2: return GetRed(ref _name, 2);
+                case 2: return GetRed(ref _name!, 2);
                 case 3: return GetRed(ref _inputDescription, 3);
-                case 4: return GetRed(ref _commas, 4);
-                case 5: return GetRed(ref _body, 5);
+                case 4: return GetRed(ref _commas!, 4);
+                case 5: return GetRed(ref _body!, 5);
+                case 6: return GetRed(ref _endKeyword, 6);
                 default: return null;
             }
         }
@@ -2086,16 +2104,16 @@ namespace Parser
 
     public class AbstractMethodDeclarationSyntaxNode : MethodDeclarationSyntaxNode
     {
-        private SyntaxNode _outputDescription;
-        private SyntaxNode _name;
-        private SyntaxNode _inputDescription;
+        private SyntaxNode? _outputDescription;
+        private SyntaxNode? _name;
+        private SyntaxNode? _inputDescription;
 
         internal AbstractMethodDeclarationSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
         }
 
 
-        public FunctionOutputDescriptionSyntaxNode OutputDescription
+        public FunctionOutputDescriptionSyntaxNode? OutputDescription
         {
             get
             {
@@ -2111,15 +2129,15 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._name, 1);
+                var red = this.GetRed(ref this._name!, 1);
                 if (red != null)
                     return (CompoundNameSyntaxNode)red;
 
-                return default(CompoundNameSyntaxNode);
+                throw new System.Exception("name cannot be null");
             }
         }
 
-        public FunctionInputDescriptionSyntaxNode InputDescription
+        public FunctionInputDescriptionSyntaxNode? InputDescription
         {
             get
             {
@@ -2131,12 +2149,12 @@ namespace Parser
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 0: return GetRed(ref _outputDescription, 0);
-                case 1: return GetRed(ref _name, 1);
+                case 1: return GetRed(ref _name!, 1);
                 case 2: return GetRed(ref _inputDescription, 2);
                 default: return null;
             }
@@ -2151,8 +2169,8 @@ namespace Parser
 
     public class MethodsListSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _attributes;
-        private SyntaxNode _methods;
+        private SyntaxNode? _attributes;
+        private SyntaxNode? _methods;
 
         internal MethodsListSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2168,7 +2186,7 @@ namespace Parser
             get { return new SyntaxToken(this, ((Parser.Internal.MethodsListSyntaxNode)_green)._endKeyword, this.GetChildPosition(3)); }
         }
 
-        public AttributeListSyntaxNode Attributes
+        public AttributeListSyntaxNode? Attributes
         {
             get
             {
@@ -2184,20 +2202,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._methods, 2);
+                var red = this.GetRed(ref this._methods!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("methods cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 1: return GetRed(ref _attributes, 1);
-                case 2: return GetRed(ref _methods, 2);
+                case 2: return GetRed(ref _methods!, 2);
                 default: return null;
             }
         }
@@ -2211,8 +2229,8 @@ namespace Parser
 
     public class PropertiesListSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _attributes;
-        private SyntaxNode _properties;
+        private SyntaxNode? _attributes;
+        private SyntaxNode? _properties;
 
         internal PropertiesListSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2228,7 +2246,7 @@ namespace Parser
             get { return new SyntaxToken(this, ((Parser.Internal.PropertiesListSyntaxNode)_green)._endKeyword, this.GetChildPosition(3)); }
         }
 
-        public AttributeListSyntaxNode Attributes
+        public AttributeListSyntaxNode? Attributes
         {
             get
             {
@@ -2244,20 +2262,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._properties, 2);
+                var red = this.GetRed(ref this._properties!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("properties cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 1: return GetRed(ref _attributes, 1);
-                case 2: return GetRed(ref _properties, 2);
+                case 2: return GetRed(ref _properties!, 2);
                 default: return null;
             }
         }
@@ -2271,7 +2289,7 @@ namespace Parser
 
     public class BaseClassListSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _baseClasses;
+        private SyntaxNode? _baseClasses;
 
         internal BaseClassListSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2286,19 +2304,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._baseClasses, 1);
+                var red = this.GetRed(ref this._baseClasses!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("baseClasses cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _baseClasses, 1);
+                case 1: return GetRed(ref _baseClasses!, 1);
                 default: return null;
             }
         }
@@ -2312,10 +2330,10 @@ namespace Parser
 
     public class ClassDeclarationSyntaxNode : StatementSyntaxNode
     {
-        private SyntaxNode _attributes;
-        private SyntaxNode _className;
-        private SyntaxNode _baseClassList;
-        private SyntaxNode _nodes;
+        private SyntaxNode? _attributes;
+        private SyntaxNode? _className;
+        private SyntaxNode? _baseClassList;
+        private SyntaxNode? _nodes;
 
         internal ClassDeclarationSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2331,7 +2349,7 @@ namespace Parser
             get { return new SyntaxToken(this, ((Parser.Internal.ClassDeclarationSyntaxNode)_green)._endKeyword, this.GetChildPosition(5)); }
         }
 
-        public AttributeListSyntaxNode Attributes
+        public AttributeListSyntaxNode? Attributes
         {
             get
             {
@@ -2347,15 +2365,15 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._className, 2);
+                var red = this.GetRed(ref this._className!, 2);
                 if (red != null)
                     return (IdentifierNameSyntaxNode)red;
 
-                return default(IdentifierNameSyntaxNode);
+                throw new System.Exception("className cannot be null");
             }
         }
 
-        public BaseClassListSyntaxNode BaseClassList
+        public BaseClassListSyntaxNode? BaseClassList
         {
             get
             {
@@ -2371,22 +2389,22 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._nodes, 4);
+                var red = this.GetRed(ref this._nodes!, 4);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("nodes cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 1: return GetRed(ref _attributes, 1);
-                case 2: return GetRed(ref _className, 2);
+                case 2: return GetRed(ref _className!, 2);
                 case 3: return GetRed(ref _baseClassList, 3);
-                case 4: return GetRed(ref _nodes, 4);
+                case 4: return GetRed(ref _nodes!, 4);
                 default: return null;
             }
         }
@@ -2400,7 +2418,7 @@ namespace Parser
 
     public class EnumerationItemValueSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _values;
+        private SyntaxNode? _values;
 
         internal EnumerationItemValueSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2420,19 +2438,19 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._values, 1);
+                var red = this.GetRed(ref this._values!, 1);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("values cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 1: return GetRed(ref _values, 1);
+                case 1: return GetRed(ref _values!, 1);
                 default: return null;
             }
         }
@@ -2446,9 +2464,9 @@ namespace Parser
 
     public class EnumerationItemSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _name;
-        private SyntaxNode _values;
-        private SyntaxNode _commas;
+        private SyntaxNode? _name;
+        private SyntaxNode? _values;
+        private SyntaxNode? _commas;
 
         internal EnumerationItemSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2459,15 +2477,15 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._name, 0);
+                var red = this.GetRed(ref this._name!, 0);
                 if (red != null)
                     return (IdentifierNameSyntaxNode)red;
 
-                return default(IdentifierNameSyntaxNode);
+                throw new System.Exception("name cannot be null");
             }
         }
 
-        public EnumerationItemValueSyntaxNode Values
+        public EnumerationItemValueSyntaxNode? Values
         {
             get
             {
@@ -2483,21 +2501,21 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._commas, 2);
+                var red = this.GetRed(ref this._commas!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("commas cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
-                case 0: return GetRed(ref _name, 0);
+                case 0: return GetRed(ref _name!, 0);
                 case 1: return GetRed(ref _values, 1);
-                case 2: return GetRed(ref _commas, 2);
+                case 2: return GetRed(ref _commas!, 2);
                 default: return null;
             }
         }
@@ -2511,8 +2529,8 @@ namespace Parser
 
     public class EnumerationListSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _attributes;
-        private SyntaxNode _items;
+        private SyntaxNode? _attributes;
+        private SyntaxNode? _items;
 
         internal EnumerationListSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2528,7 +2546,7 @@ namespace Parser
             get { return new SyntaxToken(this, ((Parser.Internal.EnumerationListSyntaxNode)_green)._endKeyword, this.GetChildPosition(3)); }
         }
 
-        public AttributeListSyntaxNode Attributes
+        public AttributeListSyntaxNode? Attributes
         {
             get
             {
@@ -2544,20 +2562,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._items, 2);
+                var red = this.GetRed(ref this._items!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("items cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 1: return GetRed(ref _attributes, 1);
-                case 2: return GetRed(ref _items, 2);
+                case 2: return GetRed(ref _items!, 2);
                 default: return null;
             }
         }
@@ -2571,8 +2589,8 @@ namespace Parser
 
     public class EventsListSyntaxNode : SyntaxNode
     {
-        private SyntaxNode _attributes;
-        private SyntaxNode _events;
+        private SyntaxNode? _attributes;
+        private SyntaxNode? _events;
 
         internal EventsListSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
         {
@@ -2588,7 +2606,7 @@ namespace Parser
             get { return new SyntaxToken(this, ((Parser.Internal.EventsListSyntaxNode)_green)._endKeyword, this.GetChildPosition(3)); }
         }
 
-        public AttributeListSyntaxNode Attributes
+        public AttributeListSyntaxNode? Attributes
         {
             get
             {
@@ -2604,20 +2622,20 @@ namespace Parser
         {
             get
             {
-                var red = this.GetRed(ref this._events, 2);
+                var red = this.GetRed(ref this._events!, 2);
                 if (red != null)
                     return (SyntaxNodeOrTokenList)red;
 
-                return default(SyntaxNodeOrTokenList);
+                throw new System.Exception("events cannot be null");
             }
         }
 
-        internal override SyntaxNode GetNode(int i)
+        internal override SyntaxNode? GetNode(int i)
         {
             switch (i)
             {
                 case 1: return GetRed(ref _attributes, 1);
-                case 2: return GetRed(ref _events, 2);
+                case 2: return GetRed(ref _events!, 2);
                 default: return null;
             }
         }
@@ -2628,4 +2646,32 @@ namespace Parser
         }
 
     }
+
+    public class EndKeywordSyntaxNode : SyntaxNode
+    {
+
+        internal EndKeywordSyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position) : base(parent, green, position)
+        {
+        }
+
+        public SyntaxToken EndKeyword
+        {
+            get { return new SyntaxToken(this, ((Parser.Internal.EndKeywordSyntaxNode)_green)._endKeyword, this.GetChildPosition(0)); }
+        }
+
+
+        internal override SyntaxNode? GetNode(int i)
+        {
+            switch (i)
+            {
+                default: return null;
+            }
+        }
+
+        public override void Accept(SyntaxVisitor visitor)
+        {
+            visitor.VisitEndKeyword(this);
+        }
+
+    }
 }
diff --git a/Parser/SyntaxNode.cs b/Parser/SyntaxNode.cs
index 3031945..117e1e2 100644
--- a/Parser/SyntaxNode.cs
+++ b/Parser/SyntaxNode.cs
@@ -7,7 +7,7 @@ namespace Parser
     public abstract class SyntaxNode
     {
         private readonly SyntaxNode _parent;
-        internal readonly Internal.GreenNode _green; 
+        internal readonly Internal.GreenNode _green;
         internal SyntaxNode(SyntaxNode parent, Internal.GreenNode green, int position)
         {
             _parent = parent;
@@ -15,6 +15,13 @@ namespace Parser
             Position = position;
         }
 
+        private protected SyntaxNode(Internal.GreenNode green, int position)
+        {
+            _parent = this;
+            _green = green;
+            Position = position;
+        }
+
         public TokenKind Kind => _green.Kind;
 
         public SyntaxNode Parent => _parent;
@@ -43,9 +50,9 @@ namespace Parser
             return result;
         }
 
-        internal abstract SyntaxNode GetNode(int index);
+        internal abstract SyntaxNode? GetNode(int index);
 
-        internal SyntaxNode GetRed(ref SyntaxNode field, int slot)
+        internal SyntaxNode? GetRed(ref SyntaxNode? field, int slot)
         {
             if (field == null)
             {
@@ -119,4 +126,35 @@ namespace Parser
         }
     }
 
+    public class RootSyntaxNode : SyntaxNode
+    {
+        private SyntaxNode? _file;
+
+        internal RootSyntaxNode(Internal.GreenNode green, int position) : base(green, position)
+        {
+        }
+
+        internal override SyntaxNode? GetNode(int index)
+        {
+            throw new System.NotImplementedException();
+        }
+
+        public override void Accept(SyntaxVisitor visitor)
+        {
+            throw new System.NotImplementedException();
+        }
+
+
+        public FileSyntaxNode File
+        {
+            get
+            {
+                var red = this.GetRed(ref this._file, 0);
+                if (red != null)
+                    return (FileSyntaxNode)red;
+
+                throw new System.Exception("file cannot be null");
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/Parser/SyntaxNodeOrToken.cs b/Parser/SyntaxNodeOrToken.cs
index c81330e..775ca93 100644
--- a/Parser/SyntaxNodeOrToken.cs
+++ b/Parser/SyntaxNodeOrToken.cs
@@ -2,7 +2,7 @@
 {
     public struct SyntaxNodeOrToken
     {
-        private readonly Internal.GreenNode _token;
+        private readonly Internal.GreenNode? _token;
         private readonly SyntaxNode _nodeOrParent;
         private readonly bool _isToken;
 
@@ -27,7 +27,7 @@
 
         public int Position { get; }
 
-        public SyntaxNode AsNode()
+        public SyntaxNode? AsNode()
         {
             if (_isToken)
             {
@@ -43,7 +43,7 @@
             {
                 return default(SyntaxToken);
             }
-            return new SyntaxToken(_nodeOrParent, _token, Position);
+            return new SyntaxToken(_nodeOrParent, _token!, Position);
         }
 
         public static implicit operator SyntaxNodeOrToken(SyntaxToken token)
diff --git a/Parser/SyntaxNodeOrTokenList.cs b/Parser/SyntaxNodeOrTokenList.cs
index 2e69337..336cff7 100644
--- a/Parser/SyntaxNodeOrTokenList.cs
+++ b/Parser/SyntaxNodeOrTokenList.cs
@@ -24,7 +24,7 @@ namespace Parser
                     }
                     else
                     {
-                        return green.CreateRed(this, this.GetChildPosition(index));
+                        return green!.CreateRed(this, this.GetChildPosition(index));
                     }
                 }
                 throw new ArgumentOutOfRangeException();
@@ -81,7 +81,7 @@ namespace Parser
 
         public int Count => _green.Slots;
         
-        internal override SyntaxNode GetNode(int index)
+        internal override SyntaxNode? GetNode(int index)
         {
             if (index < _green.Slots)
             {
diff --git a/Parser/SyntaxVisitor.Generated.cs b/Parser/SyntaxVisitor.Generated.cs
index 41e133b..c76edaa 100644
--- a/Parser/SyntaxVisitor.Generated.cs
+++ b/Parser/SyntaxVisitor.Generated.cs
@@ -251,5 +251,10 @@ namespace Parser
         {
             DefaultVisit(node);
         }
+
+        public virtual void VisitEndKeyword(EndKeywordSyntaxNode node)
+        {
+            DefaultVisit(node);
+        }
     }
 };
\ No newline at end of file
diff --git a/Parser/SyntaxVisitor.cs b/Parser/SyntaxVisitor.cs
index fc81561..b03fd73 100644
--- a/Parser/SyntaxVisitor.cs
+++ b/Parser/SyntaxVisitor.cs
@@ -2,7 +2,7 @@
 {
     public abstract partial class SyntaxVisitor
     {
-        public virtual void Visit(SyntaxNode node)
+        public virtual void Visit(SyntaxNode? node)
         {
             node?.Accept(this);
         }
diff --git a/Parser/TextWindow.cs b/Parser/TextWindow.cs
index 41d4dc5..3a604a2 100644
--- a/Parser/TextWindow.cs
+++ b/Parser/TextWindow.cs
@@ -6,7 +6,7 @@
         private Position _position;
         public Position Position => _position;
 
-        public TextWindow(string text, string fileName = null)
+        public TextWindow(string text, string? fileName = null)
         {
             Text = text;
             _position = new Position
diff --git a/Parser/TextWindowWithNull.cs b/Parser/TextWindowWithNull.cs
index 70d1aee..36d6304 100644
--- a/Parser/TextWindowWithNull.cs
+++ b/Parser/TextWindowWithNull.cs
@@ -2,7 +2,7 @@
 {
     public class TextWindowWithNull : TextWindow
     {
-        public TextWindowWithNull(string text, string fileName = null) : base(text, fileName)
+        public TextWindowWithNull(string text, string? fileName = null) : base(text, fileName)
         {
         }
 
diff --git a/Parser/TokenKind.cs b/Parser/TokenKind.cs
index e614836..52e455c 100644
--- a/Parser/TokenKind.cs
+++ b/Parser/TokenKind.cs
@@ -271,5 +271,7 @@
         //     ToggleSomething
         // end
         EventsList,
+        EndKeyword,
+        Root
     }
 }
\ No newline at end of file
diff --git a/SyntaxGenerator/GenerateSyntax.cs b/SyntaxGenerator/GenerateSyntax.cs
index 10ca108..5b68a82 100644
--- a/SyntaxGenerator/GenerateSyntax.cs
+++ b/SyntaxGenerator/GenerateSyntax.cs
@@ -15,7 +15,7 @@ namespace SyntaxGenerator
 
         private static readonly List<(string visitorMethodName, string className)> Visitors = new List<(string, string)>();
 
-        private static string _outputPath;
+        private static readonly string _outputPath;
 
         static GenerateSyntax()
         {
@@ -62,12 +62,14 @@ namespace SyntaxGenerator
 
         private static string GenerateInternalFieldDeclaration(FieldDescription field)
         {
-            return $"        internal readonly {field.FieldType} _{field.FieldName};\n";
+            return $"        internal readonly {FullFieldType(field)} _{field.FieldName};\n";
         }
 
         private static string GeneratePrivateFieldDeclaration(FieldDescription field)
         {
-            return $"        private SyntaxNode _{field.FieldName};\n";
+            //var typeDeclaration = field.FieldIsNullable ? "SyntaxNode?" : "SyntaxNode";
+            var typeDeclaration = "SyntaxNode?";
+            return $"        private {typeDeclaration} _{field.FieldName};\n";
         }
 
         private static string GenerateFieldAssignmentInsideConstructor(FieldDescription field)
@@ -81,15 +83,15 @@ namespace SyntaxGenerator
         {
             var arguments = string.Join(
                 ",",
-                node.Fields.Select(field => $"\n            {field.FieldType} {field.FieldName}"));
+                node.Fields.Select(field => $"\n            {FullFieldType(field)} {field.FieldName}"));
 
             var header =
-                $"        internal {node.ClassName}({arguments}) : base(TokenKind.{node.TokenKindName})\n";
-            var slotsAssignment = $"\n            Slots = {node.Fields.Length};\n";
+                $"        internal {node.ClassName}({arguments}) : base(TokenKind.{node.TokenKindName})";
+            var slotsAssignment = $"            Slots = {node.Fields.Length};";
             var assignments = string.Join(
                 "",
                 node.Fields.Select(GenerateFieldAssignmentInsideConstructor));
-            return header + "        {\n" + slotsAssignment + assignments + "        }\n";
+            return header + "\n        {\n" + slotsAssignment + "\n" + assignments + "        }\n";
         }
 
         private static string GenerateConstructor(SyntaxNodeDescription node)
@@ -102,7 +104,7 @@ namespace SyntaxGenerator
 
         private static string GenerateInternalGetSlot(SyntaxNodeDescription node)
         {
-            var header = $"        public override GreenNode GetSlot(int i)\n";
+            var header = $"        public override GreenNode? GetSlot(int i)\n";
             var cases = string.Join(
                 "",
                 node.Fields.Select((f, i) => $"                case {i}: return _{f.FieldName};\n"));
@@ -117,10 +119,16 @@ namespace SyntaxGenerator
         
         private static string GenerateGetSlot(SyntaxNodeDescription node, List<(FieldDescription field, int index)> pairs)
         {
-            var header = $"        internal override SyntaxNode GetNode(int i)\n";
+            var header = $"        internal override SyntaxNode? GetNode(int i)\n";
+
+            string GetFieldNameWithPossibleBang(FieldDescription field)
+            {
+                return field.FieldIsNullable ? field.FieldName : field.FieldName + "!";
+            }
+
             var cases = string.Join(
                 "",
-                pairs.Select(pair => $"                case {pair.index}: return GetRed(ref _{pair.field.FieldName}, {pair.index});\n"));
+                pairs.Select(pair => $"                case {pair.index}: return GetRed(ref _{GetFieldNameWithPossibleBang(pair.field)}, {pair.index});\n"));
             var defaultCase = "                default: return null;\n";
             return header
                    + "        {\n            switch (i)\n            {\n"
@@ -185,12 +193,17 @@ namespace SyntaxGenerator
             {
                 type = "SyntaxNodeOrTokenList";
             }
-            var header = $"        public {type} {Capitalize(field.FieldName)}\n        {{\n            get\n            {{\n";
+
+            var typeName = type + (field.FieldIsNullable ? "?" : "");
+            var header = $"        public {typeName} {Capitalize(field.FieldName)}\n        {{\n            get\n            {{\n";
+            var defaultReturnStatement = field.FieldIsNullable ? $"return default({type});" : $"throw new System.Exception(\"{field.FieldName} cannot be null\");";
+
+            var fieldNameWithPossibleBang = field.FieldIsNullable ? field.FieldName : field.FieldName + "!";
             var text =
-                $"                var red = this.GetRed(ref this._{field.FieldName}, {index});\n"
+                $"                var red = this.GetRed(ref this._{fieldNameWithPossibleBang}, {index});\n"
                 + $"                if (red != null)\n"
                 + $"                    return ({type})red;\n\n"
-                + $"                return default({type});\n";
+                + $"                {defaultReturnStatement}\n";
             return header + text + "            }\n        }\n";
         }
 
@@ -287,13 +300,18 @@ namespace SyntaxGenerator
             }
         }
 
+        private static string FullFieldType(FieldDescription field)
+        {
+            return field.FieldIsNullable ? field.FieldType + "?" : field.FieldType;
+        }
+
         private static string GenerateFactoryMethod(SyntaxNodeDescription node)
         {
             var methodName = FactoryMethodNameFromClassName(node.ClassName);
             var header = $"        public {node.ClassName} {methodName}";
             var arguments = string.Join(
                 ", ",
-                node.Fields.Select(field => $"\n            {field.FieldType} {field.FieldName}"));
+                node.Fields.Select(field => $"\n            {FullFieldType(field)} {field.FieldName}"));
             var constructorParameters = string.Join(
                 ", ",
                 node.Fields.Select(field => $"\n                {field.FieldName}"));
@@ -335,8 +353,7 @@ namespace SyntaxGenerator
             var serializer = new XmlSerializer(typeof(SyntaxDescription));
             using (var stream = new FileStream("input.xml", FileMode.Open))
             {
-                var syntax = serializer.Deserialize(stream) as SyntaxDescription;
-                if (syntax == null)
+                if (!(serializer.Deserialize(stream) is SyntaxDescription syntax))
                 {
                     Console.WriteLine("Couldn't deserialize syntax.");
                     return;
diff --git a/SyntaxGenerator/SyntaxNodeDescription.cs b/SyntaxGenerator/SyntaxNodeDescription.cs
index ef38a0c..9f60038 100644
--- a/SyntaxGenerator/SyntaxNodeDescription.cs
+++ b/SyntaxGenerator/SyntaxNodeDescription.cs
@@ -34,5 +34,7 @@ namespace SyntaxGenerator
         public string FieldType { get; set; }
         [XmlAttribute("Name")]
         public string FieldName { get; set; }
+        [XmlAttribute("Nullable")]
+        public bool FieldIsNullable { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SyntaxGenerator/input.xml b/SyntaxGenerator/input.xml
index 1bd4142..09dd3fe 100644
--- a/SyntaxGenerator/input.xml
+++ b/SyntaxGenerator/input.xml
@@ -6,12 +6,12 @@
     </Class>
     <Class Name="FunctionDeclarationSyntaxNode" BaseClass="StatementSyntaxNode" Kind="FunctionDeclaration">
         <Field Type="SyntaxToken" Name="functionKeyword" />
-        <Field Type="FunctionOutputDescriptionSyntaxNode" Name="outputDescription" />
+        <Field Type="FunctionOutputDescriptionSyntaxNode" Name="outputDescription" Nullable="true" />
         <Field Type="SyntaxToken" Name="name" />
-        <Field Type="FunctionInputDescriptionSyntaxNode" Name="inputDescription" />
+        <Field Type="FunctionInputDescriptionSyntaxNode" Name="inputDescription" Nullable="true"/>
         <Field Type="SyntaxList&lt;SyntaxToken&gt;" Name="commas" />
         <Field Type="SyntaxList" Name="body" />
-        <Field Type="SyntaxToken" Name="endKeyword" />
+        <Field Type="EndKeywordSyntaxNode" Name="endKeyword" Nullable="true"/>
     </Class>
     <Class Name="FunctionOutputDescriptionSyntaxNode" BaseClass="SyntaxNode" Kind="FunctionOutputDescription">
         <Field Type="SyntaxList" Name="outputList" />
@@ -58,7 +58,7 @@
         <Field Type="SyntaxList&lt;SyntaxToken&gt;" Name="optionalCommas" />
         <Field Type="SyntaxList" Name="body" />
         <Field Type="SyntaxList&lt;ElseifClause&gt;" Name="elseifClauses" />
-        <Field Type="ElseClause" Name="elseClause" />
+        <Field Type="ElseClause" Name="elseClause" Nullable="true" />
         <Field Type="SyntaxToken" Name="endKeyword" />
     </Class>
     <Class Name="ForStatementSyntaxNode" BaseClass="StatementSyntaxNode" Kind="ForStatement">
@@ -80,7 +80,7 @@
     <Class Name="TryCatchStatementSyntaxNode" BaseClass="StatementSyntaxNode" Kind="TryCatchStatement">
         <Field Type="SyntaxToken" Name="tryKeyword" />
         <Field Type="SyntaxList" Name="tryBody" />
-        <Field Type="CatchClauseSyntaxNode" Name="catchClause" />
+        <Field Type="CatchClauseSyntaxNode" Name="catchClause" Nullable="true" />
         <Field Type="SyntaxToken" Name="endKeyword" />
     </Class>
     <Class Name="ExpressionStatementSyntaxNode" BaseClass="StatementSyntaxNode" Kind="ExpressionStatement">
@@ -183,7 +183,7 @@
     </Class>
     <Class Name="AttributeSyntaxNode" BaseClass="SyntaxNode" Kind="Attribute">
         <Field Type="IdentifierNameSyntaxNode" Name="name" />
-        <Field Type="AttributeAssignmentSyntaxNode" Name="assignment" />
+        <Field Type="AttributeAssignmentSyntaxNode" Name="assignment" Nullable="true" />
     </Class>
     <Class Name="AttributeListSyntaxNode" BaseClass="SyntaxNode" Kind="AttributeList">
         <Field Type="SyntaxToken" Name="openingBracket" />
@@ -192,27 +192,27 @@
     </Class>
     <Class Name="MethodDefinitionSyntaxNode" BaseClass="MethodDeclarationSyntaxNode" Kind="MethodDefinition">
         <Field Type="SyntaxToken" Name="functionKeyword" />
-        <Field Type="FunctionOutputDescriptionSyntaxNode" Name="outputDescription" />
+        <Field Type="FunctionOutputDescriptionSyntaxNode" Name="outputDescription" Nullable="true" />
         <Field Type="CompoundNameSyntaxNode" Name="name" />
-        <Field Type="FunctionInputDescriptionSyntaxNode" Name="inputDescription" />
+        <Field Type="FunctionInputDescriptionSyntaxNode" Name="inputDescription" Nullable="true"/>
         <Field Type="SyntaxList&lt;SyntaxToken&gt;" Name="commas" />
         <Field Type="SyntaxList" Name="body" />
-        <Field Type="SyntaxToken" Name="endKeyword" />
+        <Field Type="EndKeywordSyntaxNode" Name="endKeyword" Nullable="true" />
     </Class>
     <Class Name="AbstractMethodDeclarationSyntaxNode" BaseClass="MethodDeclarationSyntaxNode" Kind="AbstractMethodDeclaration">
-        <Field Type="FunctionOutputDescriptionSyntaxNode" Name="outputDescription" />
+        <Field Type="FunctionOutputDescriptionSyntaxNode" Name="outputDescription" Nullable="true" />
         <Field Type="CompoundNameSyntaxNode" Name="name" />
-        <Field Type="FunctionInputDescriptionSyntaxNode" Name="inputDescription" />
+        <Field Type="FunctionInputDescriptionSyntaxNode" Name="inputDescription" Nullable="true"/>
     </Class>
     <Class Name="MethodsListSyntaxNode" BaseClass="SyntaxNode" Kind="MethodsList">
         <Field Type="SyntaxToken" Name="methodsKeyword" />
-        <Field Type="AttributeListSyntaxNode" Name="attributes" />
+        <Field Type="AttributeListSyntaxNode" Name="attributes" Nullable="true" />
         <Field Type="SyntaxList" Name="methods" />
         <Field Type="SyntaxToken" Name="endKeyword" />
     </Class>
     <Class Name="PropertiesListSyntaxNode" BaseClass="SyntaxNode" Kind="PropertiesList">
         <Field Type="SyntaxToken" Name="propertiesKeyword" />
-        <Field Type="AttributeListSyntaxNode" Name="attributes" />
+        <Field Type="AttributeListSyntaxNode" Name="attributes" Nullable="true" />
         <Field Type="SyntaxList" Name="properties" />
         <Field Type="SyntaxToken" Name="endKeyword" />
     </Class>
@@ -222,9 +222,9 @@
     </Class>
     <Class Name="ClassDeclarationSyntaxNode" BaseClass="StatementSyntaxNode" Kind="ClassDeclaration">
         <Field Type="SyntaxToken" Name="classdefKeyword" />
-        <Field Type="AttributeListSyntaxNode" Name="attributes" />
+        <Field Type="AttributeListSyntaxNode" Name="attributes" Nullable="true" />
         <Field Type="IdentifierNameSyntaxNode" Name="className" />
-        <Field Type="BaseClassListSyntaxNode" Name="baseClassList" />
+        <Field Type="BaseClassListSyntaxNode" Name="baseClassList" Nullable="true" />
         <Field Type="SyntaxList" Name="nodes" />
         <Field Type="SyntaxToken" Name="endKeyword" />
     </Class>
@@ -235,19 +235,22 @@
     </Class>
     <Class Name="EnumerationItemSyntaxNode" BaseClass="SyntaxNode" Kind="EnumerationItem">
         <Field Type="IdentifierNameSyntaxNode" Name="name" />
-        <Field Type="EnumerationItemValueSyntaxNode" Name="values" />
+        <Field Type="EnumerationItemValueSyntaxNode" Name="values" Nullable="true"/>
         <Field Type="SyntaxList&lt;SyntaxToken&gt;" Name="commas" />
     </Class>
     <Class Name="EnumerationListSyntaxNode" BaseClass="SyntaxNode" Kind="EnumerationList">
         <Field Type="SyntaxToken" Name="enumerationKeyword" />
-        <Field Type="AttributeListSyntaxNode" Name="attributes" />
+        <Field Type="AttributeListSyntaxNode" Name="attributes" Nullable="true"/>
         <Field Type="SyntaxList&lt;EnumerationItemSyntaxNode&gt;" Name="items" />
         <Field Type="SyntaxToken" Name="endKeyword" />
     </Class>
     <Class Name="EventsListSyntaxNode" BaseClass="SyntaxNode" Kind="EventsList">
         <Field Type="SyntaxToken" Name="eventsKeyword" />
-        <Field Type="AttributeListSyntaxNode" Name="attributes" />
+        <Field Type="AttributeListSyntaxNode" Name="attributes" Nullable="true" />
         <Field Type="SyntaxList" Name="events" />
         <Field Type="SyntaxToken" Name="endKeyword" />
     </Class>
+    <Class Name="EndKeywordSyntaxNode" BaseClass="SyntaxNode" Kind="EndKeyword">
+        <Field Type="SyntaxToken" Name="endKeyword" />
+    </Class>
 </Syntax>