求详解，第一种多的一层包裹到底是用来干嘛的

这种装饰器很常见，也没问过为什么

 >>> def log(func):
...     def wrapper(*args, **kwargs):
...         print "call: ", func.__name__
...         return func(*args, **kwargs)
...     return wrapper
... 
>>> @log
... def now():
...     print "It's now..."
... 
>>> now()
call:  now
It's now...

这种... 我第一次见，求详解

 >>> def log(func):
...     print "call: ", func.__name__
...     return func
... 
>>> @log
... def now():
...     print "It's now......"
... 
call:  now
>>> now()
It's now......