php domdocument unwrap first div

function unwrap_first_div($html) {
    $doc = new DOMDocument();
    $doc->loadHtml($html);
    $xpath = new DOMXPath($doc);
    $divs = $xpath->query('//div');
    if ($divs->length > 1) {
        $divs->item(0)->parentNode->replaceChild($doc->importNode($divs->item(0)->firstChild,TRUE), $divs->item(0));
    }

    return $doc->saveHTML();
}