python 循环的概念

china ={
    "江苏":
        {"南京":
             {"玄武区":
                  {"中山东路":
                       {"1路","3路","5路","9路","25路","34路","801路","805路","824路"},
                   "天路":{},
                   "后路":{}
                   },"秦淮区":{},"鼓楼区":{},"建邺区":{}
              },
         "苏州":{},
         "常州":{}
         }
,"四川":{
        "成都市":{"test":"123"},
        "绵阳市":{"区":"小泉真"}
    }
}

# print(china["江苏"]["南京"]["玄武区"])
exit_flag = False
while not exit_flag :
    for i in china:
        print(i)
    choice = input("选择进入>>>>：")
    if choice in china:
        print(choice)
        while not exit_flag:
            for i2 in china[choice]:
                print('	',i2)
            choice2 = input("选择进入2>>>>：")
            if choice2 in china[choice]:
                while not exit_flag:
                    for i3 in china[choice][choice2]:
                        print('	', i3)
                    choice3 = input("选择进入3>>>>：")
                    if choice3 in china[choice][choice2]:
                        while not exit_flag:
                            for i4 in china[choice][choice2][choice3]:
                                print('	',i4)
                            choice4 = input("选择进入4>>>>：")
                            if choice4 in china[choice][choice2][choice3]:
                                while not exit_flag:
                                    for i5 in china[choice][choice2][choice3][choice4]:
                                        print('	',i5)
                                    choice5 = input("最后一层，按b返回>>>>：")
                                    if choice5 == 'b':
                                        break
                                    elif choice5 == 'q':
                                        exit_flag =True
                            elif choice4 == 'b':
                                break
                            elif choice4 == 'q':
                                exit_flag = True
                    elif choice3 == 'b':
                        break
                    elif choice3 == 'q':
                        exit_flag = True
            elif choice2 == 'b':
                break
            elif choice2 == 'q':
                exit_flag = True
    elif choice == 'b':
        break
    elif choice == 'q':
        exit_flag = True