def test_UnknownCommand(self):
        """
        Send an invalid command.

        @return: L{Deferred} of command response
        """
        d = self._anonymousLogin()
        return self.assertCommandFailed(
            'GIBBERISH',
            ["502 Command 'GIBBERISH' not implemented"],
            chainDeferred=d)

        Send an invalid command.

        @return: L{Deferred} of command response
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp.py