function sa_load_doc_comments_addon()
{
    if (class_exists('SI_Doc_Comments')) {
        return;
    }
    require_once 'inc/Doc_Comments.php';
    SI_Doc_Comments::init();
    require_once 'inc/Doc_Comment_Notifications.php';
    SI_Doc_Comments_Notifications::init();
}
 public static function default_comment_notification_invoice_to_admin()
 {
     $path = 'notifications/';
     if (class_exists('SI_HTML_Notifications')) {
         $path = 'notifications/html/';
     }
     return SI_Doc_Comments::load_addon_view_to_string($path . 'admin-notification-comment-invoice', array(), true);
 }