code: func (pn *peernet) notifyAll(notification func(f inet.Notifiee)) {
  	pn.notifmu.Lock()
  	var wg sync.WaitGroup
  	for n := range pn.notifs {
  		// make sure we dont block
  		// and they dont block each other.
  		wg.Add(1)
  		go func(n inet.Notifiee) {
  			defer wg.Done()
  			notification(n)
  		}(n)
  	}
  	wg.Wait()
  	pn.notifmu.Unlock()
  }
docs: // notifyAll runs the notification function on all Notifiees