code: public static function setLibXmlLoaderOptions($options)
      {
          if ($options === null && defined('LIBXML_DTDLOAD')) {
              $options = LIBXML_DTDLOAD | LIBXML_DTDATTR;
          }
          self::$libXmlLoaderOptions = $options;
      }
docs: Set default options for libxml loader.
  
  @param int $options Default options for libxml loader