Python - 三级菜单优化方法 (单层循环)

 1 menu = {
......
43 }
44 current_layer = menu
45 layers = []
46 while True:
47     for k in current_layer:
48         print(k)
49     choice = input('>:').strip()
50     if not choice:continue
51     if choice in current_layer:
52         layers.append(current_layer)
53         current_layer = current_layer[choice]
54     elif choice == 'q':
55         break
56     elif choice == 'b':
57         if len(layers) != 0:
58             current_layer = layers.pop()
59         else:
60             print('-------Top!-------')