code: func (d *BoundDistributor) GetStatus(_ *dm.Quest_Desc, tok distributor.Token) (rslt *dm.Result, err error) {
  	d.Lock()
  	defer d.Unlock()
  	if tsk, ok := d.tasks[tok]; ok {
  		if tsk.done {
  			if tsk.abnorm != nil {
  				rslt = &dm.Result{AbnormalFinish: tsk.abnorm}
  			} else {
  				rslt = &dm.Result{Data: tsk.State}
  			}
  		}
  	} else {
  		rslt = &dm.Result{
  			AbnormalFinish: &dm.AbnormalFinish{
  				Status: dm.AbnormalFinish_MISSING,
  				Reason: fmt.Sprintf("unknown token: %s", tok)},
  		}
  	}
  	return
  }
docs: // GetStatus implements distributor.D