protected function findButtonByName($button)
    {
        if (! is_null($element = $this->find("input[type=submit][name='{$button}']")) ||
            ! is_null($element = $this->find("input[type=button][value='{$button}']")) ||
            ! is_null($element = $this->find("button[name='{$button}']"))) {
            return $element;
        }
    }