code: func (s HashExpireyStrategy) Purge(location, ID string, pool *redis.Pool) error {
  	cnx := pool.Get()
  	defer cnx.Close()
  
  	if _, err := cnx.Do("HDEL", location, ID); err != nil {
  		return err
  	}
  
  	return nil
  }
docs: // Purge implements the `func Purge` defined in the Strategy interface. It
  // assumes a HASH type is used in Redis to map the IDs of various Hearts,
  // and removes the record for the specified ID from the hash.