code: def update_or_expire_session(self):
          
          if not hasattr(self, 'key'):
              return
          now = time.time()
          timestamp = float(self.get() or 0) or now
          sess_id = self.sess_id or UserSessionID(self.user_id).get()
          if sess_id and now - timestamp > self.SESSION_EXPIRE_TIME:
              Session(sess_id).delete()
              return False
          else:
              self.set(now)
              return True
docs: Deletes session if keepalive request expired
          otherwise updates the keepalive timestamp value