有兩種類型的回調函數：
代碼如下:
blocking callbacks (also known as synchronous callbacks or just callbacks)
deferred callbacks (also known as asynchronous callbacks)

那么，在python中如何實現回調函數呢，看代碼：

代碼如下:
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)