三级循环菜单

data={
    '北京':{
        '昌平':{
            '沙河':["oldboy","test"],
            '天通苑':["链家地产","我爱我家"],
        },
        '朝阳':{
            '望京':["奔驰","陌陌"],
            '国贸':["CICC","HP"],
            '东直门':["Advent","飞信"]
        },
        '海淀':{}
    },
    '山东':{
        '德州':{},
        '青岛':{},
        '济南':{}
    },
    '广东':{
        '东莞':{},
        '常熟':{},
        '佛山':{}
    },
}

while True:
    for i in data:
        print(i)
    choice=input("请选择菜单：")
    if choice in data:
        while True:
            for i1 in data[choice]:
                print("\t",i1)
            choice1 = input("请选择菜单：")
            if choice1 in data[choice]:
                while True:
                    for i2 in data[choice][choice1]:
                        print("\t\t",i2)
                    choice2 = input("请选择菜单：")
                    if choice2 in data[choice][choice1]:
                            for i3 in data[choice][choice1][choice2]:
                                print("\t\t\t",i3)
                            choice3=input("最后一层，按b返回")
                            if choice3=="b":
                                pass  elif choice3=="q":
                                exit()
                    if choice2=="b":
                        break  elif choice2 == "q":
                        exit()
            if choice1 == "b":
                break  elif choice1 == "q":
                exit()