def test_headersComparison(self):
        """
        A L{Headers} instance compares equal to itself and to another
        L{Headers} instance with the same values.
        """
        first = Headers()
        first.setRawHeaders(u"foo\u00E1", [u"panda"])
        second = Headers()
        second.setRawHeaders(u"foo\u00E1", [u"panda"])
        third = Headers()
        third.setRawHeaders(u"foo\u00E1", [u"lemur", u"panda"])

        self.assertEqual(first, first)
        self.assertEqual(first, second)
        self.assertNotEqual(first, third)

        # Headers instantiated with bytes equivs are also the same
        firstBytes = Headers()
        firstBytes.setRawHeaders(b"foo\xe1", [b"panda"])
        secondBytes = Headers()
        secondBytes.setRawHeaders(b"foo\xe1", [b"panda"])
        thirdBytes = Headers()
        thirdBytes.setRawHeaders(b"foo\xe1", [b"lemur", u"panda"])

        self.assertEqual(first, firstBytes)
        self.assertEqual(second, secondBytes)
        self.assertEqual(third, thirdBytes)

        A L{Headers} instance compares equal to itself and to another
        L{Headers} instance with the same values.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http_headers.py