code: def find_message_handler(self, handler_name, handler_type='primary'):
          
          ret = lib.EnvFindDefmessageHandler(
              self._env, self._cls, handler_name.encode(), handler_type.encode())
          if ret == 0:
              raise CLIPSError(self._env)
  
          return MessageHandler(self._env, self._cls, ret)
docs: Returns the MessageHandler given its name and type for this class.