code: func (k *Kite) OnRegister(handler func(*protocol.RegisterResult)) {
  	k.handlersMu.Lock()
  	k.onRegisterHandlers = append(k.onRegisterHandlers, handler)
  	k.handlersMu.Unlock()
  }
docs: // OnRegister registers a callback which is called when a Kite registers
  // to a Kontrol.