def test_expire(self):
        """
        L{server.Session.expire} expires the session.
        """
        self.session.expire()
        # It should be gone from the session dictionary.
        self.assertNotIn(self.uid, self.site.sessions)
        # And there should be no pending delayed calls.
        self.assertFalse(self.clock.calls)

        L{server.Session.expire} expires the session.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_web.py