def test_getAllRawHeaders(self):
        """
        L{Headers.getAllRawHeaders} returns an iterable of (k, v) pairs, where
        C{k} is the canonicalized representation of the header name, and C{v}
        is a sequence of values.
        """
        h = Headers()
        h.setRawHeaders(u"test\u00E1", [u"lemurs"])
        h.setRawHeaders(u"www-authenticate", [u"basic aksljdlk="])
        h.setRawHeaders(u"content-md5", [u"kjdfdfgdfgnsd"])

        allHeaders = set([(k, tuple(v)) for k, v in h.getAllRawHeaders()])

        self.assertEqual(allHeaders,
                          set([(b"WWW-Authenticate", (b"basic aksljdlk=",)),
                               (b"Content-MD5", (b"kjdfdfgdfgnsd",)),
                               (b"Test\xe1", (b"lemurs",))]))

        L{Headers.getAllRawHeaders} returns an iterable of (k, v) pairs, where
        C{k} is the canonicalized representation of the header name, and C{v}
        is a sequence of values.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http_headers.py