code: func (k Key) Identity() Identity {
  	ids := make([]Identity, 0, len(k.Identities))
  	for _, i := range k.Identities {
  		ids = append(ids, i)
  	}
  	sort.Slice(ids, func(i, j int) bool {
  		return ids[i].CreationDate.After(ids[j].CreationDate)
  	})
  	for _, i := range ids {
  		return i
  	}
  	return Identity{}
  }
docs: // Identity returns the first identity