python字典简单的三层嵌套

因为在网上没找到简单的创建三层字典的方法所以自己摸索着写了，直接上代码

menu = {}
city1 =['bj']
citybj_1 =['cy','hd']
citybj_1_gs =['sohu','bd']

for i in city1:
    for j in citybj_1:
        for k in citybj_1_gs:
            menu[i]={}
            menu[i][j]={}
            menu[i][j][k]={}
print(menu)

 运行结果