code: func NewChangeWatchResp(ctx context.Context, delegate datasync.ProtoWatchResp, prevVal datasync.LazyValue) *ChangeWatchResp {
  	return &ChangeWatchResp{
  		ctx: ctx,
  		changes: []datasync.ProtoWatchResp{
  			&changePrev{
  				ProtoWatchResp: delegate,
  				prev:           prevVal,
  			},
  		},
  		DoneChannel: &syncbase.DoneChannel{DoneChan: nil},
  	}
  }
docs: // NewChangeWatchResp creates a new instance of ChangeWatchResp.