public static function file_output($file, $options=null) {
        $id = '';
        if (!is_array($options)) {
            $options = array();
        }
        if (!array_key_exists('entry', $options)) {
            $options['entry'] = true;
        }
        if (!empty($options['entry'])) {
            $path = 'portfolio:' . self::file_id_prefix() . $file->get_id();
        } else {
            $path = self::get_file_directory() . $file->get_filename();
        }
        $attributes = array();
        if (!empty($options['attributes']) && is_array($options['attributes'])) {
            $attributes = $options['attributes'];
        }
        $attributes['rel']    = 'enclosure';
        return self::make_tag($file, $path, $attributes);
    }