python小程序--Three（三级菜单）

#!/usr/bin/env python
# _*_ coding:utf8 _*_
 
data = {
    "山东省":{
        "滨州市":{"惠民县","沾化县","无棣县","邹平县","阳信县"},
        "济南市":{"济阳县","商河县","平阴县","历下区","天桥区"},
        "菏泽市":{"定陶县","单县","巨野县","东明县","开发区"},
        "德州市":{"德城区","夏新县","平原县","陵县","乐陵县"}
    },
    "北京市":{
        "海淀区":{"航天科工","航天科技"},
        "朝阳区":{"巨人教育","老男孩教育"},
        "丰台区":{"下埔","岳各庄"}
    },
    "湖北省":{
        "武汉市":{"武昌区","江汉区","洪山区"},
        "荆州市":{"青山区","硚口区","江夏区"},
        "襄樊市":{"新洲区","南山区","北山区"}
    }
}
 
exit_flag = False
 
while not exit_flag:
    for i in data:
        print(i)
    choice = input("请选择进入：")
    if choice in data:
        while not exit_flag:
            for i1 in data[choice]:
                print("\t",i1)
            choice1 = input("请选择进入：")
            if choice1 in data[choice]:
                for i2 in data[choice][choice1]:
                    print("\t\t",i2)
                choice2 = input("最后一层，输入b，返回：")
                if choice2 == "b":
                    pass
                elif choice2 == "q":
                    exit_flag = True
            if choice1 == "b":
                break
            elif choice1 == "q":
                exit_flag = True