anchor.diff:      : ':version'
       ;
   
  +RS_Model //  for model responses
  +    : 'model'
  +    ;
  +
   UndefinedSymbol:
       Sym (Digit | Sym)*;
   
  -ModelResponse
  -    : 'model'
  -    ;
   
   // Parser Rules Start
   
  
positive.code:     ;
  
  get_model_response
      : ParOpen ModelResponse model_response* ParClose
      ;
  
  get_option_response
  
negative.code:     | GRW_Numeral
      | GRW_Par
      | GRW_String
      | RS_Model
      ;
  
  
  