def test_STORBeforePORT(self):
        """
        Send STOR before sending PORT.

        @return: L{Deferred} of command response
        """
        d = self._anonymousLogin()
        return self.assertCommandFailed(
            'STOR foo',
            ["503 Incorrect sequence of commands: "
             "PORT or PASV required before STOR"],
            chainDeferred=d)

        Send STOR before sending PORT.

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