def test_allNewStyle(self):
        """
        The L{IListeningPort} object is an instance of a class with no
        classic classes in its hierarchy.
        """
        reactor = self.buildReactor()
        port = self.getListeningPort(reactor, ServerFactory())
        self.assertFullyNewStyle(port)

        The L{IListeningPort} object is an instance of a class with no
        classic classes in its hierarchy.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_tcp.py