product_list = [('iphone',8000),                 ('bike',1000),                 ('car',200000),                 ('watch',50000)] shop_list = [] for i,v in enumerate(product_list):     print(i,v) while True:     money = input("请输入你的钱数:")     if money.isdigit():         money = int(money)         while True:             choice = input("请输入商品序号，退出输入：q:")             if choice.isdigit():                 choice = int(choice)                 if choice >= 0 and choice < len(product_list):                     item = product_list[choice]                     if money >= item[1]:                         shop_list.append(item)                         money -= item[1]                         print("%s 加入你的购物车，还剩%d元" % (item, money))                     else:                         print("你的钱不够，买个毛线")                 else:                     print("没有这个商品")             elif choice == "q":                 print("-------你买了这些商品-------")                 for j in shop_list:                     print(j)                 print("还剩%d" % money)                 qw = 1                 break             else:                 print("输入无效")         if qw == 1 :             break     else:         print("输入有问题，请重新输入")