python回调函数的使用方法

有两种类型的回调函数：

blocking callbacks (also known as synchronous callbacks or just callbacks)
deferred callbacks (also known as asynchronous callbacks)

那么，在python中如何实现回调函数呢，看代码：

def my_callback(input):
    print "function my_callback was called with %s input" % (input,)

def caller(input, func):
    func(input)

for i in range(5):
    caller(i, my_callback)