code: func (db *BytesConnectionEtcd) Watch(resp func(keyval.BytesWatchResp), closeChan chan string, keys ...string) error {
  	for _, key := range keys {
  		err := watchInternal(db.Logger, db.etcdClient, closeChan, key, resp)
  		if err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // Watch starts subscription for changes associated with the selected keys.
  // Watch events will be delivered to <resp> callback.
  // closeCh is a channel closed when Close method is called.It is leveraged
  // to stop go routines from specific subscription, or only goroutine with
  // provided key prefix