code: func (ev *DoneChannel) Done(err error) {
  	if ev.DoneChan != nil {
  		select {
  		case ev.DoneChan <- err:
  			// sent successfully
  		default:
  			logrus.DefaultLogger().Debug("Nobody is listening anymore")
  		}
  	} else if err != nil {
  		logrus.DefaultLogger().Error(err)
  	}
  }
docs: // Done propagates error to the channel.