public static function get_template_part($slug, $name = null)
 {
     if (is_null(self::$template_loader)) {
         self::$template_loader = new Testimonials_Widget_Template_Loader();
     }
     ob_start();
     self::$template_loader->get_template_part($slug, $name);
     $content = ob_get_clean();
     return $content;
 }