code: func (u *UUID) UnmarshalText(text []byte) error {
  	id := make([]byte, base64.StdEncoding.DecodedLen(len(text)))
  	length, err := base64.StdEncoding.Decode(id, text)
  	if err != nil {
  		return err
  	}
  	if length != 16 {
  		return ErrInvalidUUIDLength
  	}
  	copy((*u)[:], id[:16])
  	return nil
  }
docs: // UnmarshalText unmarshals a byte slice into a UUID by decoding the given data from base64