def cleanup(data, protos, port):
            """
            Make sure IOCPReactor didn't start several WSARecv operations
            that clobbered each other's results.
            """
            self.assertEqual(data, b'x'*(2*4096) + b'y'*(2*4096),
                                 'did not get the right data')
            return DeferredList([
                    maybeDeferred(protos[0].transport.loseConnection),
                    maybeDeferred(protos[1].transport.loseConnection),
                    maybeDeferred(port.stopListening)])

            Make sure IOCPReactor didn't start several WSARecv operations
            that clobbered each other's results.
            
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_tcp.py