小编Use*_*ser的帖子

我是python中的新手,我在使用global指令方面遇到了很多麻烦.
这是一个代码示例:

mouse = "a"
background = "b"

list_ab = [mouse, background]

def func ():
    for item in list_ab:
        global item  # I want to modify the GLOBAL item, which is mouse
                     # and background.
        item = "modified"
    print mouse  # must be "modified" not "a"
    print background  # must be "modified" not "b"

这就是问题.我该如何解决？