public function removePurchasable(
        CartInterface $cart,
        PurchasableInterface $purchasable,
        $quantity
    ) {
        /**
         * If quantity is not a number or is 0 or less, product is not removed
         * from cart.
         */
        if (!is_int($quantity) || $quantity <= 0) {
            return $this;
        }

        foreach ($cart->getCartLines() as $cartLine) {
            /**
             * @var CartLineInterface $cartLine
             */
            if (
                (get_class($cartLine->getPurchasable()) === get_class($purchasable)) &&
                ($cartLine->getPurchasable()->getId() == $purchasable->getId())
            ) {
                /**
                 * Product already in the Cart, decrease quantity.
                 */

                return $this->decreaseCartLineQuantity($cartLine, $quantity);
            }
        }

        return $this;
    }