code: func (ct *ClaimTree) FindActive(ownerID *identity.ID, t primitive.KeyType) (*apitypes.PublicKeySegment, error) {
  	for _, pks := range ct.PublicKeys {
  		if *pks.PublicKey.Body.OwnerID != *ownerID {
  			continue
  		}
  
  		if pks.PublicKey.Body.KeyType != t {
  			continue
  		}
  
  		if pks.Revoked() {
  			continue
  		}
  
  		return &pks, nil
  	}
  
  	return nil, ErrMissingKeyForOwner
  }
docs: // FindActive returns the PublicKeySegment for a non-revoked Public Key for
  // the given owner id.
  //
  // If an active key cannot be found an error is returned