code: func (b *Broadcaster) blockQueue(f func()) {
  	var wg sync.WaitGroup
  	wg.Add(1)
  	b.incoming <- Event{
  		Type: internalRunFunctionMarker,
  		Object: functionFakeRuntimeObject(func() {
  			defer wg.Done()
  			f()
  		}),
  	}
  	wg.Wait()
  }
docs: // Execute f, blocking the incoming queue (and waiting for it to drain first).
  // The purpose of this terrible hack is so that watchers added after an event
  // won't ever see that event, and will always see any event after they are
  // added.