code: async function retrieveUserFromRedis(res, auth, tokenOrEmail, config) {
    if (config.redisClient) {
      const getFromRedis = util
        .promisify(config.redisClient.get)
        .bind(config.redisClient);
      const cachedUserData = await getFromRedis(`${ns}:${tokenOrEmail}`);
      if (cachedUserData) {
        const data = JSON.parse(cachedUserData);
        const user = auth.createAuthFromData(data);
        auth.currentUser = user;
        res.locals = res.locals || {};
        res.locals.auth = auth;
        return user;
      }
    }
  }
docs: Get User from Redis Client
  @param  {!Response} res
  @param  {!Auth} auth
  @param  {!string} tokenOrEmail
  @param  {!Object} config
  @return {Auth}