/**
  * Output a warning message, of the type that appears on the admin notifications page.
  * @param string $message the message to display.
  * @param string $type type class
  * @return string HTML to output.
  */
 protected function warning($message, $type = '')
 {
     if ($type == 'error') {
         return bootstrap::alert_error($message);
     }
     if ($type == '') {
         return bootstrap::alert_error($message);
     }
     // what other types are there?
     return bootstrap::alert($type, "warning type:{$type}" . $message);
 }