def buildProtocol(self, addr):
        """
        Create the protocol instance and keeps track of it.
        """
        proto = portforward.ProxyClientFactory.buildProtocol(self, addr)
        self.protoInstance = proto
        return proto

        Create the protocol instance and keeps track of it.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_protocols.py