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function applyDiscount(string $coupon) {
	$is_unused = Sale\DiscountCouponsManager::getEnteredCoupon($coupon);
	if(!$is_unused) {
		Sale\DiscountCouponsManager::add($coupon);
		$oBasket = Sale\Basket::loadItemsForFUser(
		    Sale\Fuser::getId(),
		    Main\Context::getCurrent()->getSite()
		);
		$oDiscounts = Sale\Discount::loadByBasket($oBasket);
		$oBasket->refreshData(['PRICE', 'COUPONS']);
		$oDiscounts->calculate();
		$oDiscounts->getApplyResult();
	}
}