notify::add PHP Method

    public static function add($type, $messages)
    {
        if (!in_array($type, static::$types)) {
            return;
        }
        if (!is_array($messages)) {
            $messages = array($messages);
        }
        $key = sprintf('messages.%s', $type);
        $messages = array_merge(Session::get($key, array()), $messages);
        Session::put($key, $messages);
    }