public function addDiscount(DiscountReturnObject $discount): void 	{ 		$this->discounts[] = $discount;  		if ($discount instanceof GeneralDiscountReturnObject) { 			$this->generalDiscountApplied = $discount->isGeneralDiscount(); 			$this->generalDiscountAddsUp = $discount->doesAddUp(); 		}  		$this->currentlyCalculatedPrice = MathMoneyOperations::calculate($this->currentlyCalculatedPrice, $discount->getAmount(), '-'); 	}