python3--尝试写一个三级菜单

#!/usr/bin/env python
# coding: utf-8
__author__ = 'www.py3study.com'
class city_info(object):
    def __init__(self):
        self.list = {
                    '湖北省': {
                        '武汉市': ['新洲', '武昌', '汉口', '汉阳'],
                        '黄冈市': ['麻城', '黄陂', '罗田', '英山'],
                        '咸宁市': ['通城', '通山', '嘉鱼', '崇阳'],
                        '孝感市': ['汉川', '应城', '云梦', '安陆'],
                    },
                    '湖南省': {
                        '郴州市': ['湖区', '苏仙', '贵阳', '桂东'],
                        '衡阳市': ['珠晖', '石鼓', '常宁', '衡山'],
                        '长沙市': ['芙蓉', '天心', '开福', '雨花'],
                        '湘潭市': ['雨湖', '岳塘', '韶山', '湘乡'],
                    },
                    '广东省': {
                        '广州市': ['越秀', '东山', '天河', '白云'],
                        '惠州市': ['龙门', '博罗', '惠城', '惠阳'],
                        '东莞市': ['莞城', '东城', '南城', '万江'],
                        '佛山市': ['南海', '顺德', '高明', '三水'],
                    },
                    '广西省': {
                        '南宁市': ['江南', '良庆', '武鸣', '青秀'],
                        '桂林市': ['秀峰', '叠彩', '象山', '雁山'],
                        '玉林市': ['北流', '陆川', '玉州', '福绵'],
                        '柳州市': ['柳南', '鱼峰', '城中', '柳北'],
                    }
        }
        self.run()

    def run(self):
        while True:
            content = input("是否打印省列表:\nY/y(yes/Yes)打印省列表\nQ/q(quit/QUIT)退出程序\
            \n输入你的选择:").strip()
            if content.upper() == 'Y' or content.upper() == 'YES':
                self.sheng()
                return True
            elif content.upper() == 'Q' or content.upper() == 'QUIT':
                exit()
            else:
                print("输入有误!")

    def sheng(self):
        while True:
            self.sheng_index = list(self.list.keys())
            for i in self.sheng_index:
                print("\t{}\t{}\t".format(self.sheng_index.index(i)+1, i))
            self.sheng_content = input("选择序号: 省--->打印市\nB/b(back/BACK)返回上级选项\
            \nQ/q(quit/QUIT)退出程序!\n输入你的选择:").strip()
            if self.sheng_content.isdigit():
                self.sheng_content = int(self.sheng_content)
                if 0 < self.sheng_content <= len(self.sheng_index):
                    self.sheng_content -= 1
                    self.city_shi = list(self.list[self.sheng_index[self.sheng_content]].keys())
                    #print(self.city_shi)
                    for s in self.city_shi:
                        print("\t{}\t{}\t".format(self.city_shi.index(s)+1, s))

                    self.shi()
                    return True
                else:
                    print("输入的省序号不存在!")
            elif self.sheng_content.upper() == 'B' or self.sheng_content.upper() == 'BACK':
                self.run()
                return True
            elif self.sheng_content.upper() == 'Q'or self.sheng_content.upper() == 'QUIT':
                exit()
            else:
                print("error(非法字符)")

    def shi(self):
        while True:
            self.shi_content = input("选择序号 市---->打印县 :\nB/b(back/BACK)返回上级选项\
            \nQ/q(quit/QUIT)退出程序!\n输入你的选择:").strip()
            if  self.shi_content.isdigit():
                self.shi_content = int(self.shi_content)
                if 0 < self.shi_content <= len(self.city_shi):
                    self.shi_content = int(self.shi_content) - 1
                    self.shi_xian = \
                    list(self.list[self.sheng_index[self.sheng_content]][self.city_shi[self.sheng_content]])
                    sum1 = 0
                    for i in self.shi_xian:
                        sum1 +=1 < len(self.shi_xian)
                        print("\t{}\t{}\t".format(sum1, i))
                    self.xian()
                    return True
                else:
                    print("输入的市序号不存在！")
            elif self.shi_content.upper() == 'B' or self.shi_content.upper() == 'BACK':
                self.sheng()
                return True
            elif self.shi_content.upper() == 'Q' or self.shi_content.upper() == 'QUIT':
                exit()
            else:
                print("输入错误!")
    def xian(self):
        while True:
            self.xian_content = input("***************end***************\nB/b(back/BACK)返回上级选项\
            \nT/t(top/TOP)返回顶部\nQ/q(quit/QUIT)退出程序!\n输入你的选择:").strip()
            if self.xian_content.upper() == 'B' or self.xian_content.upper() == 'BACK':
                self.shi()
                return True
            elif self.xian_content.upper() == 'T' or self.xian_content.upper() == 'TOP':
                self.run()
                return True
            elif self.xian_content.upper() == 'Q' or self.xian_content.upper() == 'QUIT':
                exit()
            else:
                print("输入错误")

if __name__ == '__main__':
    st = city_info()