def tearDown(self):
        """
        Disconnect the client/server pair and shutdown the port created in
        L{setUp}.
        """
        self.connector.disconnect()
        return defer.gatherResults([
            self.serverConnLost, self.clientConnLost,
            defer.maybeDeferred(self.port.stopListening)])

        Disconnect the client/server pair and shutdown the port created in
        L{setUp}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_tcp.py