这个代码怎么写啊，商品检测数量 python

class CheckNumError(Exception):
    def __init__(self, message):
        self.message = message


li = []
def shopping():
    all_total = 0
    goods_dict = {"五常大米": 45.00, "五丰河粉": 29.90, "农家大米": 45.00, "纯香香油": 22.90}
    print("名称  价格")
    print("按q退出")
    for name, price in goods_dict.items():
        print(f"{name}  {price}￥")
    while True:
        # 购物车列表
        cart_dict = {}
        # 商品名称
        goods_name = input("请输入选购的商品名称:\n")
        if goods_name == 'q':
            break
        # 商品数量
        else:
            try:
                goods_num = int(input("请输入选购的数量:\n"))
                if goods_num < 1:
                    raise CheckNumError('选购商品数量至少为1件，已默认添加1件{}到购物车'.format(goods_name))
            except CheckNumError as e:
                print(e)
                goods_num = 1
            cart_dict['名称'] = goods_name
            cart_dict['数量'] = goods_num
            li.append(cart_dict)
    for i in li:
        total = goods_dict[i['名称']] * i['数量']
        all_total += total
    print(f'总消费{all_total}元')


if __name__ == '__main__':
    shopping()