def test_indexing(self):
        """
        A L{TunnelAddress} instance can be indexed to retrieve either the byte
        string C{"TUNTAP"} or the name of the tunnel interface, while
        triggering a deprecation warning.
        """
        address = TunnelAddress(TunnelFlags.IFF_TAP, "tap0")
        self.assertEqual("TUNTAP", address[0])
        self.assertEqual("tap0", address[1])
        warnings = self.flushWarnings([self.test_indexing])
        message = (
            "TunnelAddress.__getitem__ is deprecated since Twisted 14.0.0  "
            "Use attributes instead.")
        self.assertEqual(DeprecationWarning, warnings[0]['category'])
        self.assertEqual(message, warnings[0]['message'])
        self.assertEqual(DeprecationWarning, warnings[1]['category'])
        self.assertEqual(message, warnings[1]['message'])
        self.assertEqual(2, len(warnings))

        A L{TunnelAddress} instance can be indexed to retrieve either the byte
        string C{"TUNTAP"} or the name of the tunnel interface, while
        triggering a deprecation warning.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/pair/test/test_tuntap.py