public static function updateInventoryOnPurchase($args) {
        global $usces;

        $items = $args['cart'];
        foreach ($items as $index => $item) {
            $sels = unserialize($item['serial']);
            // combo-set ID not set, continue
            if (empty($sels['comboSetId'])) {
                continue;
            }
            // combo-set group items not set, continue
            if (!isset($sels['comboSetItems'])) {
                continue;
            }

            // make each group item quantity the same as the combo-set item quant
            foreach ($sels['comboSetItems'] as $serial => $gitem) {
                $sels['comboSetItems'][$serial]['quant'] = (int)$gitem['quant'] * $item['quantity'];
            }
            $realcart = $_SESSION['usces_cart'];
            $_SESSION['usces_cart'] = $sels['comboSetItems'];
            // loop combo-set group items and update inventory for each one
            usces_action_reg_orderdata_stocks(['cart' => $usces->cart->get_cart()]);
            $_SESSION['usces_cart'] = $realcart;
        }
    }