code: func (x *XC) findPublicKey(needle string) (*keyring.PublicKey, error) {
  	for _, id := range x.pubring.KeyIDs() {
  		if id == needle {
  			return x.pubring.Get(id), nil
  		}
  	}
  	return nil, fmt.Errorf("no sender found for id '%s'", needle)
  }
docs: // findPublicKey tries to find a given public key in the keyring