code: func (p *Client) HandleNotification(req []byte) {
  	p.Lock()
  	defer p.Unlock()
  	vh := att.HandleValueIndication(req).AttributeHandle()
  	sub, ok := p.subs[vh]
  	if !ok {
  		// FIXME: disconnects and propagate an error to the user.
  		log.Printf("Got an unregistered notification")
  		return
  	}
  	fn := sub.nHandler
  	if req[0] == att.HandleValueIndicationCode {
  		fn = sub.iHandler
  	}
  	if fn != nil {
  		fn(req[3:])
  	}
  }
docs: // HandleNotification ...