三级菜单的实现

还是有不行的地方，先记录一下，往下学习在继续完善。

china = {'辽宁省':{'沈阳':['和平区','太原街','中街'],
                    '大连':['甘井子','瓦房店','金州区'],
                    '朝阳':['朝阳县','凌源','北票']},
         '吉林省':{'蛟河':['新农','天北镇','前进乡'],
                    '吉林':['永吉县','丰满区','龙潭区'],
                    '长春':['朝阳区','绿园区','宽城区']},
         }

import time
province = []
city = []
info = True
while info:
    print("".center(13,"="),"欢迎使用","".center(13,"="))
    print("".center(36,"="))
    for key, value in enumerate(china.keys(),1):
        print(key,value)
        province.append(value)
    print("退出请按q")
    print("".center(36,"="))

    number1 = input("please entry your number:")
    print("".center(36, "="))
    if number1 == 'q' or number1 == 'Q':
        exit()
    if number1.isdigit():
        number1 = int(number1)

        if number1 <= len(province) and number1 > 0 :
            for key,value in enumerate(china[province[number1 - 1]].keys(),1):
                print(key,value)
                city.append(value)
            print("退出请按q或Q","返回上一级请按b或B")
            print("".center(36, "="))

            number2 = input("please entry your number:")
            print("".center(36, "="))
            if number2 == 'q' or number2 == 'Q':
                info = False
            elif number2 == 'b' or number2 == 'B':
                del province[:]
                del city[:]


            elif number2.isdigit():
                number2 = int(number2)
                if number2 <= len(city) and number2 > 0 :
                    while info:
                        for name in china[province[number1 - 1]][city[number2 - 1]]:
                            print(name)
                        print("退出请按q或Q","返回上一级请按b或B")
                        print("".center(36, "="))
                        number3 = input("please entry your number:")
                        if number3 == 'q' or number3 == 'Q':
                            info = False

                        elif number3 == 'b' or number3 == 'B':
                            del city[:]
                            
                            
            else:
                print("输入错误！！")
                time.sleep(1)
    else:
        print("输入错误!!")
        time.sleep(3)