def test_sendUnimplemented(self):
        """
        Test that unimplemented messages are sent correctly.  Payload::
            uint32 sequence number
        """
        self.proto.sendUnimplemented()
        self.assertEqual(
            self.packets, [(transport.MSG_UNIMPLEMENTED,
                            b'\x00\x00\x00\x00')])

        Test that unimplemented messages are sent correctly.  Payload::
            uint32 sequence number
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_transport.py