     * @param int $n - number of model form.
     */
    public function copyModel(int $n = -1): void
    {
        if ($n === -1) {
            $selector = "div.item:last-child button[class*='copy']";
        } else {
            $selector = "div.item:nth-child($n) button[class*='copy']";
        }
        $this->clickElement($selector);
    }

    /**