def setUp(self):
        """
        Create a site with one active session using a deterministic, easily
        controlled clock.
        """
        self.clock = Clock()
        self.uid = b'unique'
        self.site = server.Site(resource.Resource())
        self.session = server.Session(self.site, self.uid, self.clock)
        self.site.sessions[self.uid] = self.session

        Create a site with one active session using a deterministic, easily
        controlled clock.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_web.py