python 的装饰器解释

 1 import time
 2 def timeit(fn):
 3     def wrap(*args,**kwargs):
 4         start = time.time()
 5         fn(*args,**kwargs)
 6         print (time.time() - start)
 7     return wrap
 8     
 9 def sleep(x):
10     time.sleep(x)

11 timeit(sleep)(3)
12 3.003286123275757
13 
14 
15 @timeit
16 def sleep(x):
17     time.sleep(x)
18 
19 sleep(2)
20 
21 
22 2.00276517868042

分解开就是:
fn  = timeit(sleep)
fn(3)

3.00378155708313