public static function get_instance()
 {
     if (!self::$_instance) {
         self::$_instance = new feu_content_attribute_helper();
     }
     return self::$_instance;
 }
 function get_content_attributes($content_type)
 {
     $tmp = array();
     $attr = new CmsContentTypeProfileAttribute('feu_groups', 'visitors');
     $attr->set_helper(feu_content_attribute_helper::get_instance());
     $tmp[] = $attr;
     return $tmp;
 }