python day-2 三级目录做业

zone = {    "广东":{ "广州":{ "天河":["天河体育馆","暨南大学"],                        "越秀":["越秀公园","五羊"]                  },              "深圳":{ "福田":["市民中心","平安大厦"],                        "南山":["腾讯","世界之窗"]                  }            },    "湖北":{ "武汉":{ "武昌":["武汉大学","华科大"],                        "汉口":["汉正街","火车站"]                  },              "鄂州":{ "鄂城":["武商","西山"],                        "葛店":["开发区","电厂"]                  }            }}exit_flag = Falsewhile not exit_flag:    for i in zone:        print(i)    choice = input("请选择：")    if choice in zone :        while not exit_flag:            for i2 in zone[choice]:                print(i2)            choice2 = input("请选择2：")            if choice2 in zone[choice]:                while not exit_flag:                    for i3 in zone[choice][choice2]:                        print(i3)                    choice3 = input("请选择3：")                    if choice3 in zone[choice][choice2]:                        for i4 in zone[choice][choice2][choice3]:                            print(i4)                        choice4 = input("最后一级，请按b返回")                        if choice4 == "b" :                            pass                        elif choice4 == "q":                            exit_flag = True                    if choice3 == "b" :                        break                    elif choice3 == "q" :                        exit_flag = True            if choice2 == "b":                break            elif choice2 == "q":                exit_flag = True    elif choice == "q" :        break