/**
  * is_quizfile
  *
  * @param xxx $sourcefile
  * @return xxx
  */
 public static function is_quizfile($sourcefile)
 {
     // e.g. http://www.qedoc.net/library/PLJUB_019.zip
     $search = '/http:\\/\\/www\\.qedoc.(?:com|net)\\/library\\/\\w+\\.zip/i';
     return preg_match($search, $sourcefile->get_source());
     // Note: we may want to detect the following as well:
     // http://www.qedoc.net/qqp/jnlp/PLJUB_019.jnlp
 }