private function _findFile(string $dirName, string $fileName): ?FileHandler {
        $dirs = glob($dirName . '*');
        $file = null;
        foreach ($dirs as $d) {
            if (is_file($d)) {
                $pathInfo = \pathinfo($d);
                $pathInfo2 = \pathinfo($fileName);

                if (isset($pathInfo2["extension"])) {
                    $condition = $pathInfo["basename"] === $pathInfo2["basename"];
                } else {
                    $condition = $pathInfo["filename"] === $pathInfo2["filename"];
                }

                if ($condition) {
                    return new FileHandler($dirName . "/" . $pathInfo["basename"]);
                }
            } else if (is_dir($d)) {
                $tmp = $this->_findFile($d . "/", $fileName);
                if (null !== $tmp) {
                    $file = $tmp;
                }
            }
        }
        return $file;
    }