Python如何创建装饰器时保留函数元信息

import time
from functools import wraps
def timethis(func):
  '''
  Decorator that reports the execution time.
  '''
  @wraps(func)
  def wrapper(*args, **kwargs):
    start = time.time()
    result = func(*args, **kwargs)
    end = time.time()
    print(func.__name__, end-start)
    return result
  return wrapper

> @timethis
... def countdown(n):
...   '''
...   Counts down
...   '''
...   while n > 0:
...     n -= 1
...
> countdown(100000)
countdown 0.008917808532714844
> countdown.__name__
'countdown'
> countdown.__doc__
'\n\tCounts down\n\t'
> countdown.__annotations__
{'n': <class 'int'>}
>

> countdown.__name__
'wrapper'
> countdown.__doc__
> countdown.__annotations__
{}
>

> countdown.__wrapped__(100000)
>

> from inspect import signature
> print(signature(countdown))
(n:int)
>