code: func (r *RedisStorer) All() ([]string, error) {
  	var sessions []string
  
  	iter := r.client.Scan(0, "", 0).Iterator()
  	for iter.Next() {
  		sessions = append(sessions, iter.Val())
  	}
  	err := iter.Err()
  	return sessions, errors.Wrap(err, "unable to iterate redis store")
  }
docs: // All keys in the redis store