Three-level menu (and are using recursion stack implementation)

the MENU = {
     ' Beijing ' : {
         ' Haidian ' : {
             ' Wudaokou ' : {
                 ' SOHO ' : {},
                 ' NetEase ' : {},
                 ' Google ' : {}},
             ' Zhongguancun ' : {
                 ' iQIYI ' : {},
                 ' car home ' : {},
                 ' excellent cool " : {}
            }
        }
    },
    ' Shanghai ' : {},
     ' Guangdong ' : {
         ' Guangzhou ' : {
             ' clouds ' : {
                 ' Baiyun Mountain ' : {},
                 ' Guangdong University of Foreign Studies ' : {}
            },
            ' Panyu ' : {
                 ' Guangzhou University City ' : {
                     ' Guangdong University of Technology ' : {
                         ' second canteen ' : {
                             ' grilled chicken with rice '
                        },
                        ' East thirteen before ' : {
                             ' a couple of Poe '
                        }
                    },
                    ' South China University of Technology ' : {},
                     ' Sun Yat-sen ' : {}
                }
            }
        },
        ' Chaoshan ' : {
             ' jieyang ' : {
                 ' jieyang Teachers University ' : {},
                 ' jieyang INSTITUTE (construction) " : {},
            },
            ' Shantou ' : {
                 ' STU ' : {}
            }
        }
    }
}

Recursive method:

def tri_menu(dic):
    while True:
        for k in dic:
            print(k)
        key = input('请输入地址：').strip()
        if key == 'b' or key == 'q':
            return key
        elif key in dic.keys() and dic[key]:
            ret = tri_menu(dic[key])
            if ret == 'q':
                return 'q'


tri_menu(menu)

Stack method:

li = [menu]
while li:
    for key in li[-1]:
        print(key)
    K = INPUT ( ' Enter location: ' ) .strip ()
     IF K in Li [-1] .keys () and Li [-1 ] [K]:
        Li.append (Li [ -1 ] [K])
     Elif K == ' . b ' :
        li.pop ()
    elif k == 'q':
        break
    else:
        continue