code: func NewDefaultRedisStorer(addr, password string, db int) (*RedisStorer, error) {
  	if addr == "" {
  		addr = "localhost:6379"
  	}
  	opts := redis.Options{
  		Addr:     addr,
  		Password: password,
  		DB:       db,
  	}
  	return NewRedisStorer(opts, time.Hour*24*2)
  }
docs: // NewDefaultRedisStorer takes a bind address of the Redis server host:port and
  // returns a RedisStorer object with default values.
  // The default values are:
  // Addr: localhost:6379
  // Password: no password
  // DB: First database (0) to be selected after connecting to Redis
  // maxAge: 2 days (clear session stored in Redis after 2 days)