anchor.diff:      | enumeration
       | selfReference
       | nameAndTypeArguments
  -    ;
  -    
  -selector 
  -    : memberSelector
  -    | argumentsWithFunctionalArguments
  -    -> ^(CALL_EXPR argumentsWithFunctionalArguments)
  -    | elementSelector
  -    -> ^(SUBSCRIPT_EXPR elementSelector)
  -    | postfixOperator 
  -    -> ^(POSTFIX_EXPR postfixOperator)
       ;
   
   memberSelector
  
positive.code:     INTERFACE_BODY;
      MEMBER_DECL;
      MEMBER_NAME;
      BROKEN_MEMBER_BODY;
      METHOD_ARG;
      METHOD_DECL;
  
negative.code:     ;
  
  directiveStatement
      : directive ';'?
      -> ^(DIRECTIVE directive)
      ;
  
  directive
  