code: func (s *redisStorage) Set(key string, val interface{}, expires time.Duration) error {
  	item := &cachedItem{Val: val}
  	value, err := encodeGob(item)
  	if err != nil {
  		return err
  	}
  
  	status := s.c.SetEx(key, expires, string(value))
  	return status.Err()
  }
docs: // Set sets value to given key in session.