def test_opt_datetimeMissingOpenQuote(self):
        """
        A line that does not begin with a double quote (C{"}) is
        parsed as L{None}, and the remainder is the whole line.
        """
        line = b'not "'
        dt, remainder = self.server.opt_datetime(line)
        self.assertIsNone(dt)
        self.assertEqual(remainder, line)

        A line that does not begin with a double quote (C{"}) is
        parsed as L{None}, and the remainder is the whole line.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py