def test_unknownParams(self):
        """
        Parsing and serializing Via headers with unknown parameters should work.
        """
        s = "SIP/2.0/UDP example.com:5060;branch=a12345b;bogus;pie=delicious"
        v = sip.parseViaHeader(s)
        self.assertEqual(v.toString(), s)

        Parsing and serializing Via headers with unknown parameters should work.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sip.py