Function log

tests/BS_thread_pool_test.cpp:371–377

 */
template <typename... T>
void log(const T&... items)
{
    if (use_stdout)
        sync_cout.print(items...);
    if (use_log)
        sync_log.print(items...);
}

/**
 * @brief Print any number of items to the standard output and/or the log file, followed by a newline character.