code: func decodeKey(k string) (string, error) {
  	if !strings.HasPrefix(k, encodedKeyPrefix) {
  		return "", fmt.Errorf("encoded key missing prefix (%s)", encodedKeyPrefix)
  	}
  
  	data, err := keyEncoding.DecodeString(k[len(encodedKeyPrefix):])
  	if err != nil {
  		return "", fmt.Errorf("failed to decode key: %v", err)
  	}
  	return string(data), nil
  }
docs: // decodeKey converts an encoded key into its original key string.