auto now = std::chrono::steady_clock::now();
    std::chrono::duration<double> diff = std::chrono::steady_clock::now() - now;
    std::cout << "now: " << diff.count() << std::endl;
    std::this_thread::sleep_for(std::chrono::duration<int>(5));
    diff = std::chrono::steady_clock::now() - now;
    std::cout << "sleep_for: " << diff.count() << std::endl;