code: func (ch *channel) ackRequest(ok bool) error {
  	if !ch.decided {
  		return errUndecided
  	}
  
  	var msg interface{}
  	if !ok {
  		msg = channelRequestFailureMsg{
  			PeersId: ch.remoteId,
  		}
  	} else {
  		msg = channelRequestSuccessMsg{
  			PeersId: ch.remoteId,
  		}
  	}
  	return ch.sendMessage(msg)
  }
docs: // ackRequest either sends an ack or nack to the channel request.