code: RuleReturnScope invoke(Parser parser) throws Exception
      {
          assert parser != null;
  
          return (RuleReturnScope)method.invoke(parser, arguments);
      }
docs: Invoke the selected parser method with its arguments
  
  @param parser the parser whose method will be invoked
  @return the <code>RuleReturnScope</code> returned by the parser
  @throws Exception if an error occurs