按任意键选择，返回，退出

按数字键选择任意城市、地区等，按b返回上一级菜单重新选择，按q退出整个程序

import sys

haidian=['guotu','zhongguancun']
chaoyang=['shoutu','dayuecheng']
pudong=['mingzhu','waitan']
dongfang=['dong','fang']

beijing={'haidian':haidian,'chaoyang':chaoyang}
shanghai={'pudong':pudong,'dongfang':dongfang}
city={'beijing':beijing,'shanghai':shanghai}


while True:
    for x,y in enumerate(city):
        print x+1,y
    num_c=raw_input('Please enter a number to choose a city,or press b back to previous menu,or press q to quit:')

    if num_c == 'q':
        sys.exit()
    if num_c is not None: #此处需要细化判断输入字符是否合规
        for x,y in enumerate(city):
            if x+1 == int(num_c):
                city_choice = y
                print 'Your choice is : %s' %city_choice

            
                while True:
                    for x,y in enumerate(city[city_choice]):
                        print x+1,y
                    num_d=raw_input('Please enter a number to choose a district,or press b back to previous menu,or press q to quit:')
                    if num_d == 'q':
                        sys.exit()
                    if num_d == 'b': #返回到上一级选择城市的菜单
                        break
                    if num_d is not None:
                        for x,y in enumerate(city[city_choice]):  #枚举city['beijing']
                            if x+1 == int(num_d):
                                dt_choice = y
                                print 'Your choice is : %s' %dt_choice


                                while True:
                                    for x,y in enumerate(city[city_choice][dt_choice]): #枚举city['beijing']['haidian']
                                        print x+1,y
                                    num_s=raw_input('Please enter a number to choose a place,or press b back to previous menu,or press q to quit:')
                                    if num_s == 'q':
                                        sys.exit()
                                    if num_s == 'b': #返回到上一级选择地区的菜单
                                        break
                                    if num_s is not None:
                                        for x,y in enumerate(city[city_choice][dt_choice]):
                                            if x+1 == int(num_s):
                                                l_choice = y
                                                print 'Your choice is : %s' %l_choice