protected function getFileModifiedTimestampOfFile($fileName, $format = 'Y-m-d H:i:s', $resultInUtc = false)
    {
        if (!file_exists($fileName)) {
            return ['error' => $fileName . ' was not found'];
        }
        $info = new \SplFileInfo($fileName);
        if ($format === 'PHPtime') {
            return $info->getMTime();
        }
        $sReturn = date($format, $info->getMTime());
        if ($resultInUtc) {
            $sReturn = gmdate($format, $info->getMTime());
        }
        return $sReturn;
    }