RemoveListener not support closure function

[RelicOfTesla]

func makeFn(a int) event.ListenerFunc {
	return func(e event.Event) error {
		fmt.Println(a)
		return nil
	}
}
func main() {
	evBus := event.NewManager("")
	f1 := makeFn(11)
	evBus.On("evt1", f1)
	f2 := makeFn(22)
	evBus.On("evt1", f2)
	evBus.RemoveListener("evt1", f1) // DON'T REMOVE ALL !!!
	evBus.MustFire("evt1", event.M{"arg0": "val0", "arg1": "val1"})
}