code: func (u *UUID) decodeURN(t []byte) (err error) {
  	total := len(t)
  
  	urn_uuid_prefix := t[:9]
  
  	if !bytes.Equal(urn_uuid_prefix, urnPrefix) {
  		return fmt.Errorf("uuid: incorrect UUID format: %s", t)
  	}
  
  	return u.decodePlain(t[9:total])
  }
docs: // decodeURN decodes UUID string in format
  // "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8" or in format
  // "urn:uuid:6ba7b8109dad11d180b400c04fd430c8".