private static function selectPackage(string $pathname): string {
    $filename = $pathname . DIRECTORY_SEPARATOR . 'lang' . DIRECTORY_SEPARATOR . Lang::$locale . ".json";
    if (file_exists($filename)) {
      $pathname = $filename;
    } else {
      $pathname .= DIRECTORY_SEPARATOR . 'lang' . DIRECTORY_SEPARATOR . Lang::STANDARD_LOCALE . ".json";
    }
    return $pathname;
  }