docs: async def load(self, request):
          """Load session from cookies."""
          if SESSION_KEY not in request:
              session = Session(self.cfg.secret, key=self.cfg.session_cookie,
                                max_age=self.cfg.max_age, domain=self.cfg.domain)
              session.load(request.cookies)
              self.app.logger.debug('Session loaded: %s', session)
              request[SESSION_KEY] = request.session = session
          return request[SESSION_KEY]