code: func (s *Store) importPublicKey(ctx context.Context, r string) error {
  	for _, kd := range []string{keyDir, oldKeyDir} {
  		filename := filepath.Join(kd, r)
  		if !s.storage.Exists(ctx, filename) {
  			out.Debug(ctx, "Public Key %s not found at %s", r, filename)
  			continue
  		}
  		pk, err := s.storage.Get(ctx, filename)
  		if err != nil {
  			return err
  		}
  		return s.crypto.ImportPublicKey(ctx, pk)
  	}
  	return fmt.Errorf("public key not found in store")
  }
docs: // import an public key into the default keyring