python3之三级菜单

 city = {
     "江苏省": {
         "南京市": {
             "栖霞区": ["aa", "bb"],
             "顺义区": ["cc", "dd"],
             "普陀区": ["ee", "ff"]
         },
         "南通市": {
             "通州区": ["gg", "hh"],
             "港闸区": ["ii", "jj"],
             "崇川区": ["kk", "ll"]
         },
     },
     "浙江省": {
         "杭州市": {
             "A区": ["mm", "nn"],
             "B区": ["oo", "pp"]
         },
         "温州市": {
             "C区": ["qq", "rr"],
             "D区": ["ss", "tt"]
         }
     }
 }
 current_layer = city
 layers = []
 while True:
     print("欢迎来到省市区信息管理系统".center(50, "*"))
     for layer in current_layer:
         print(layer)
     choice = input("请输入你要查看的省市区信息,返回上一级按b，退出按q").strip()
     # 查看
     if choice in current_layer:
         layers.append(current_layer)
         current_layer = current_layer[choice]
     elif choice == "b":
         current_layer = layers.pop()
     elif choice == "q":
         break
     else:
         print("到底了！")