code: func (helper *CacheHelper) DoChange(dataChng datasync.ProtoWatchResp) error {
  	var err error
  	switch dataChng.GetChangeType() {
  	case datasync.Put:
  		current := proto.Clone(helper.DataPrototype)
  		dataChng.GetValue(current)
  		name, err := helper.ParseName(dataChng.GetKey())
  		if err == nil {
  			helper.IDX.Put(name, current)
  		}
  	case datasync.Delete:
  		name, err := helper.ParseName(dataChng.GetKey())
  		if err == nil {
  			helper.IDX.Delete(name)
  		}
  	}
  	return err
  }
docs: // DoChange calls:
  // - Put in case of datasync.Put
  // - Delete in case of data.Del