anchor.diff:  	| ArrowStar
   	| Arrow
   	| LeftParen RightParen
  -	| LeftBracket RightBracket;+	| LeftBracket RightBracket;
  +
  +literal:
  +	IntegerLiteral
  +	| CharacterLiteral
  +	| FloatingLiteral
  +	| StringLiteral
  +	| BooleanLiteral
  +	| PointerLiteral
  +	| UserDefinedLiteral;
  
positive.code: /*Expressions*/
  
  primaryExpression:
  	Literal+
  	| This
  	| LeftParen expression RightParen
  	| idExpression
  
negative.code: 	captureList
  	| captureDefault (Comma captureList)?;
  
  captureDefault: And | Assign;
  
  captureList: capture (Comma capture)* Ellipsis?;
  
  