anchor.diff:          )* RPAR
           {
               $json = jsonArray;
  +        }
  +    ;
  +
  +
  +value_list returns [Object json]
  +    :   non_variable_value_list
  +        {
  +            $json = $non_variable_value_list.json;
           }
       |   VARIABLE
           {
  
positive.code:         }
      ;
  
  value_list returns [Object json]
  @init {
      JSONArray jsonArray = new JSONArray();
  }
  
negative.code:     ;
  
  facet_param returns [String facet, JSONObject param]
      :   LPAR column_name COMMA STRING_LITERAL COMMA facet_param_type COMMA (val=value | valList=non_variable_value_list) RPAR
          {
              $facet = $column_name.text; // XXX Check error here?
              try {
  