Three-level menu Lite

# _ * _ Coding: UTF-8 _ * _ 
# Author: Wang Dian-yuan 
# Date: 2019/12/14 
the MENU = { 
    'Shanghai': { 
        'Minhang District': { 
            'old Minhang': { 
                'Zizhu Science Park': {} , 
                'Shanghai Jiao Tong University': {} 
            } 
            'new Minhang': { 
                'River town': {}, 
                'Caohejing': {} 
            } 
        }, 
        'Huangpu District': { 
            'Bund': { 
                'Pearl of the Orient ': {}, 
                ' Nanjing pedestrian Street ': {}, 
                ' Yuyuan ': {} 
            }, 
            ' building ': { 
                ' people's Square ': {}, 
                ' Theater ': {},
            } 
        } 
    }, 
    'Shenzhen': {
        'Futian District': { 
            'Huaqiang North': { 
                'Huaqiang Electronic City': {}, 
                'SEG Electronic City': {} 
            } 
            'Walking Street': { 
                'East Gate Walking Street': {}, 
                'Lychee Park ': {} 
            } 
        }, 
        ' Nanshan District ': { 
            ' Science Park ': { 
                ' Nanshan Science and Technology Park ': {}, 
                ' Xili Technology Park ': {} 
            } 
            ' phone garden ': { 
                ' Cool Science Park ': {}, 
                ' OPPO Technology Park ':} {, 
            }, 
        }, 
    }, 
} 
MSG =' ''******* ******* Please enter the area 
    input b Return to the previous 
    enter q to quit 
********************************************************** ' '' 
current_layer = MENU
= parent_layers [] 
user_enter_quit = False 
the while not user_enter_quit: 
    Print (msg) 
    for Key in current_layer: 
        Print (Key) 
    user_enter the INPUT = ( "Please the INPUT:") 
    IF user_enter in current_layer: 
        parent_layers.append (current_layer) every current # layer corresponds to the additional dictionary list 
        current_layer = current_layer [user_enter] # dictionary assigned next layer the current layer 
    elif user_enter.lower () == 'B' and parent_layers = []:! 
        current_layer parent_layers.pop = () # default Removes the last element in the list, and returns the element value. Does not increase the length of the list using the pop 
    elif user_enter.lower () == 'Q': 
        user_enter_quit = True 
    the else: 
        ( '! Please Enter Again') Print