public function getFlash($index)
    {
        if ( ! $this->isOpened()) {
            $this->start();
        }
        $_oldf = null;
        if (!empty($index) && isset($this->old_flashes[$index])) {
            $_oldf = $this->old_flashes[$index];
            unset($this->old_flashes[$index]);
            return $_oldf;
        }
        return null;
    }