template<class Evt>
class Multicast{
public:
    template<class Fn>
    void addObserver(Fn&& obs){
        observers.push_back(obs);
    }

    void broadcast(Evt event){
        for ( auto& obs : observers ){
            obs(event);
        }
    }
private:
    std::vector< std::function<void(Evt)> > observers;
};