python元组，列表，字典练习

#coding = utf-8goods_data = (["iphone7",8000],["mac pro",12000],["bike",1000])
buyed_goods =[]
def display_menu():    mes = '''
    ******购物商城系统******
        1.%s    %d
        2.%s    %d
        3.%s    %d
        4.退出系统
    ************************
    '''%(goods_data[0][0],goods_data[0][1],goods_data[1][0],goods_data[1][1],goods_data[2][0],goods_data[2][1])
    print(mes)
def showbought(buyed_goods):
    length = len(buyed_goods)
    mes = '''
    ---购物清单---
    '''
    print(mes)
    for i in(buyed_goods):
        print(i)
def toselect():
    display_menu()
    selected = int(input("请选择："))
    return selected
yue = int(input("输入金额："))
while True:
    se =toselect()
    if(se == 1 and yue >= goods_data[0][1] ):
        buyed_goods.append([goods_data[0][0],goods_data[0][1]])
        yue -= goods_data[0][1]
        print("购买商品%s成功,花费%d RMB,余额为：%d" % (goods_data[0][0], goods_data[0][1],yue))
        continue    if(se ==2 and yue >= goods_data[1][1]):
        buyed_goods.append([goods_data[1][0], goods_data[1][1]])
        yue -= goods_data[1][1]
        print("购买商品%s成功,花费%d RMB,余额为：%d" % (goods_data[1][0], goods_data[1][1], yue))
        continue    if(se ==3 and yue >= goods_data[2][1]):
        buyed_goods.append([goods_data[2][0], goods_data[2][1]])
        yue -= goods_data[2][1]
        print("购买商品%s成功,花费%d RMB,余额为：%d" % (goods_data[2][0], goods_data[2][1],yue))
        continue
    else:
        print("余额不足！！！")
        showbought(buyed_goods)
        break