Level four menu implementation (Python)

menu_dict = {
' Shandong ': {
' Qingdao ': {
' Quartet ': {' Xinglong road ', ' Pingan road ', ' Hangzhou Road '},
' Huangdao ': {},
' Laoshan ': {}
         },
' Jinan ': {
' Licheng ': {},
' Huaiyin ': {},
' High-tech ': {}
         },
     },
' Jiangsu ': {
' Suzhou ': {
' Canglang ': {},
' Xiangcheng ': {},
' Pingjiang ': {}
         },
' Nanjing ': {
' Baixia ': {},
' Qinhuai ': {},
' Pukou ': {}
         }
     }
}

Current_layer = menu_dict
parent_layers = [] #把不同层级的字典保存在列表中 (nested dictionary in list) [menu_dict,menu_dict[Province], .... ], to the last level, the list looks like this.
#parent_layers [0]={' Shandong ': {' Qingdao ': {' Sifang ': {' Hangzhou road ', ' Xinglong Road ', ' Pingan Road '}, ' Huangdao ': {}, ' Laoshan ': {}}, ' Jinan ': {' Licheng ': {}, ' Huaiyin ': {}, ' High-tech ': {} }}, ' Jiangsu ': {' Suzhou ': {' Canglang ': {}, ' Xiangcheng ': {}, ' Pingjiang ': {}}, ' Nanjing ': {' Baixia ': {}, ' Qinhuai ': {}, ' Pukou ': {} }}

#parent_layers[1]={' qingdao ': {' Sifang ': {' Hangzhou road ', ' Xinglong Road ', ' Pingan Road '}, ' Huangdao ': {}, ' Laoshan ': {}}, ' Jinan ': {' Licheng ': {}, ' Huaiyin ': {}, ' High ': {}}}

 #parent_layers[2]={' quartet ': {' Hangzhou road ', ' Xinglong Road ', ' Pingan Road '}, ' Huangdao ': {}, ' Laoshan ': {}} whileTrue:

 For key in Current_layer:
 Print (key)
 Choice = input (">>:"). Strip ()
 If len (choice) = = 0:
 Continue
 If choice in Current_layer:
 Parent_layers.append (Current_layer)

 Current_layer = Current_layer[choice]
 elif Choice = = ' B ':
 If Parent_layers:
 Current_layer = Parent_layers.pop ()
 Else
 Print ("No this item")

Level four menu implementation (Python)