anchor.diff:  fragment LetterOrDigit : [a-zA-Z0-9$_];
   
   
  -COMMA : '!';
  -QUOTE : '\'';
  -
  -WS :  (' '|'\r'|'\t'|'\u000C'|'\n')+ -> skip;
  +COMMA : '!'|',';
  +QUOTE : '\'';
positive.code:  ;
  
  argumentList
   : sourceElement+
   | ('!'? (literal | identifierVal)+ '!'?)+
   | literal (COMMA? literal)*
   ;
  
  expression
    : identifierName arguments                        # CallExpression
    | Identifier (('.' Identifier)+)?                 # FieldExpression
    ;
  
  identifierName : Identifier;
  
negative.code: NullLiteral
   : 'null'
   | 'nil'
   | 'N'
   ;
  
  BooleanLiteral
   : 'true' | 'T'
   | 'false' | 'F'
   ;
  
  StringLiteral
  