def __init__(self, site, uid, reactor=None):
        """
        Initialize a session with a unique ID for that session.
        """
        components.Componentized.__init__(self)

        if reactor is None:
            from twisted.internet import reactor
        self._reactor = reactor

        self.site = site
        self.uid = uid
        self.expireCallbacks = []
        self.touch()
        self.sessionNamespaces = {}

        Initialize a session with a unique ID for that session.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/server.py