code: func (idserv *V1IDService) Set(v1ID, registry string, id layer.DiffID) error {
  	if idserv.store == nil {
  		return nil
  	}
  	if err := v1.ValidateID(v1ID); err != nil {
  		return err
  	}
  	return idserv.store.Set(idserv.namespace(), registry+","+v1ID, []byte(id))
  }
docs: // Set associates an image with a V1 ID.