三级菜单

The following code is 3 level menu, which is based on the list. But there is still some errors I can't fix them: we can't go back main menu by pressing "b", even this command doesn't exist, I don't know if it is PyCharm's problem. I wii try to fix them later.

#多级字典及嵌套操作

city_province = {

    "SiChuan" : {
        "ChengDu": {
                    "JingJiangQu": ["银石广场", "春熙路"],
                    "WuHouQu": ["武侯祠"]

                    },
        "MianYang":["345"],
        "DeYang":["678"],
        "LuZhou":["789"],
        "PanZhiHua":["91011"],
        "LeShan":["101112"],
        "GuangAn":["111213"]
    },
    "GuiZhou": {
        "GuiYang": ["123"],
        "ZunYiShi": ["234"],
        "AnShunShi": ["345"],
        "FuQuanShi": ["456"],
        "KaiLiShi": ["567"],
        "XingYiShi": ["678"]
    },
    "YunNan": {
        "KunMing": ["123"],
        "QuJing": ["234"],
        "YuXi": ["345"],
        "BaoShan": ["456"],
        "LiJiang": ["567"],
        "PuEr": ["678"],
        "XuanWei": ["789"]
    }


}

# print(city_province["YunNan"]["KunMing"][0])
# print(city_province.values())
# print(city_province.keys())

while True:
    for index, i in enumerate(city_province):
        print(index, i)

    choice = input("input your province: ")
    if choice in city_province:
        while True:
            for i2 in city_province[choice]:
                print("	", i2)
            choice_2 = input("input your city:")
            if choice_2 in city_province[choice]:
                while True:
                    for i3 in city_province[choice][choice_2]:
                        print("		", i3)
                    choice_3 = input("input your choice to get more details: ")
                    if choice_3 in city_province[choice]:
                        for i4 in city_province[choice][choice_2][choice_3]:
                            print("		", i4)
                        choice_4 = input("press b to go back the main menu: ")
                        if choice_4 == "b":
                           pass
                if choice_3 == "b":
                    break
        if choice_2 == "b":
            break