code: protected static function normalizeUrl($url)
      {
          $fs = new Filesystem();
          if ($fs->isAbsolutePath($url)) {
              return 'file://' . strtr($url, '\\', '/');
          }
  
          return $url;
      }
docs: An absolute path (leading '/') is converted to a file:// url.
  
  @param string $url
  
  @return string