public static function checkDivisions($cart) {
        $mes = '';
        foreach ($cart as $i => $cart_row) {
            $sels = unserialize($cart_row['serial']);
            $mapifiedselections = [];
            $errors = [];
            if (!empty($sels['comboSetId']) && !empty($sels['comboSetItems'])) {
                foreach ($sels['comboSetItems'] as $giserial => $gitem) {
                    $data = unserialize($giserial);
                    $mapifiedselections[$data['groupId']][] = $data['itemId'];
                    $result = self::comboSetItemDivisionIsValid($sels['comboSetId'], $mapifiedselections);
                    if ($result instanceof GenericError) {
                        $errors[] = $result->message;
                    }
                }
            }

            $mes .= self::constructIndexedErrorMessage($i, $errors);
        }

        return $mes;
    }