def test_interfaceTCP(self):
        """
        TCP port descriptions parse their 'interface' argument as a string.
        """
        self.assertEqual(
            self.parse('tcp:80:interface=127.0.0.1', self.f),
            ('TCP', (80, self.f), {'interface': '127.0.0.1', 'backlog': 50}))

        TCP port descriptions parse their 'interface' argument as a string.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py