class ShoppingCart:
    def __init__(self):
        self.items = []

    def add_item(self, price):
        self.items.append(price)

    def get_total(self):
        self.items = sum(self.items) * 0.9


shop = ShoppingCart()
shop.add_item(10000)
shop.add_item(20000)
shop.get_total()
print(shop.items)