trace call time

template <typename callable, typename ... arguments>
    static float trace(callable && f, arguments &&... args)
    {
        std::function<typename std::result_of<callable(arguments...)>::type()> 
            task(std::bind(std::forward<callable>(f), std::forward<arguments>(args)...));
        std::chrono::time_point<std::chrono::system_clock> start = std::chrono::system_clock::now();
        task();
        std::chrono::duration<float> dt(std::chrono::system_clock::now() - start);
        return dt.count();
    }