def test_oldAddress(self):
        """
        The C{type} of the host address of a listening L{DatagramProtocol}'s
        transport is C{"UDP"}.
        """
        server = Server()
        d = server.startedDeferred = defer.Deferred()
        p = reactor.listenUDP(0, server, interface="127.0.0.1")
        def cbStarted(ignored):
            addr = p.getHost()
            self.assertEqual(addr.type, 'UDP')
            return p.stopListening()
        return d.addCallback(cbStarted)

        The C{type} of the host address of a listening L{DatagramProtocol}'s
        transport is C{"UDP"}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_udp.py