Method ms

tests/BS_thread_pool_test.cpp:3462–3465

* @brief Get the number of milliseconds stored when `stop()` was last called. * * @return The number of milliseconds. */

     * @return The number of milliseconds.
     */
    [[nodiscard]] std::chrono::milliseconds::rep ms() const
    {
        return (std::chrono::duration_cast<std::chrono::milliseconds>(elapsed_time)).count();
    }

private:
    /**