python 购物小程序

#货物清单
product_list = [('Iphone',5800),
                ('Mac Pro',12000),
                ('coffee',31),
                ('Book',120),
                ('Bycle',800)]
#购物车清单
shopping_list = []
#顾客输入自己的工资
salary = input("请输入您的工资：")
if salary.isdigit():
    salary = int(salary)
while True:
    for index,item in enumerate(product_list):
        print(index,item)
    usr_choice = input("请选择你要商品：")
    if usr_choice.isdigit():
        usr_choice = int(usr_choice)
        if usr_choice < len(product_list) and usr_choice>=0:
            p_item = product_list[usr_choice]
            print(p_item)
            if salary >= p_item[1]:    #可以购买
                shopping_list.append(p_item)
                salary-=p_item[1]
                print("添加 %s 到你的购物车,你现在余额还剩 \033[31;1m%s\033[0m" %(p_item,salary))
            else:
                print("\033[41;1m您的余额不足!\033[0m")
        else:
            print("\033[33;1m您选的商品不存在！\033[0m")
    elif usr_choice =='Q':
        print("------打印购物清单-----")
        for i in shopping_list:
            print(i)
        print("你的余额还剩：\033[31;1m%s\033[0m"%(salary))
        exit()
    else:
        print("\033[31;1m 你输入无效!\033[0m")