router.go
func (r *Router) NotFound(i interface{}) {
	handler := r.buildHandler(i)
	r.dispatcher.NotFoundHandler(r.route, handler)
}
func (r *Router) NotFound(i interface{}) {
	handler := r.buildHandler(i)
	r.dispatcher.NotFoundHandler(r.route, handler)
}
// NotFound specifys a not found handler for a route