code: def undefine(self):
          
          if lib.EnvUndefmessageHandler(self._env, self._cls, self._idx) != 1:
              raise CLIPSError(self._env)
  
          self._env = None
docs: Undefine the MessageHandler.
  
          Python equivalent of the CLIPS undefmessage-handler command.
  
          The object becomes unusable after this method has been called.