code: func (b base57) Decode(u string) (uuid.UUID, error) {
  	str, err := b.stringToNum(u)
  	if err != nil {
  		return uuid.Nil, err
  	}
  	return uuid.Parse(str)
  }
docs: // Decode decodes a string according to the alphabet into a uuid.UUID. If s is
  // too short, its most significant bits (MSB) will be padded with 0 (zero).