function updPromo()
{
    $promo = params("promo");
    $newLabel = params("newLabel");
    $promoToUpd = Promo::getPromoByPromo($promo);
    $promoToUpd->setLabel($newLabel);
    $status = $promoToUpd->update();
    set("status", $status);
    header('Content-Type: application/json');
    return render("status.json.php");
}