public static function init_microtime($alert_threshold = null, $force_show_file = false)
    {
        if(DebugTool::$enabled)
        {
            DebugTool :: $start_microtime  = microtime(true);
            DebugTool :: $last_microtime   = DebugTool :: $start_microtime;
            DebugTool :: $alert_threshold  = $alert_threshold;
            DebugTool :: $force_show_file  = $force_show_file;
        }
    }