server.go
func (mux *ServerMux) HandleFunc(r router.Router, h HandlerFunc, v view.View) {
	mux.routers.Add(r, h, v)
}
func (mux *ServerMux) HandleFunc(r router.Router, h HandlerFunc, v view.View) {
	mux.routers.Add(r, h, v)
}
// HandleFunc specifies a pair of handler and view to handle
// the request witch matching router.