protected function logInFile($txt = '', $logFile = '/tmp/llh.log')
    {
        if (! is_string($txt)) {
            $txt = print_r($txt, true);
        }

        $txt = '==> '.date('Y/m/d H:i:s').' ==> '.$txt."\n";

        if (self::$logInFileFirst === true) {
            file_put_contents($logFile, $txt);

            self::$logInFileFirst = false;
        } else {
            file_put_contents($logFile, $txt, FILE_APPEND);
        }
    }