def test_http11(self):
        """
        After being used for an I{HTTP/1.1} request, the L{HTTPChannel} is
        persistent.
        """
        persist = self.channel.checkPersistence(self.request, b"HTTP/1.1")
        self.assertTrue(persist)
        self.assertEqual(
            [], list(self.request.responseHeaders.getAllRawHeaders()))

        After being used for an I{HTTP/1.1} request, the L{HTTPChannel} is
        persistent.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http.py