method-decorator.md

>>> def wrap(f):
...     # NOTE: self は args[0] に入る
...     def _wrap(*args, **kwargs):
...         print('Before')
...         res = f(*args, **kwargs)
...         print('After')
...         return res
...     return _wrap
... 
>>> 
>>> class Example:
...     @wrap
...     def greet(self):
...         print('Hello, World!')
... 
>>> o = Example()
>>> o.greet()
Before
Hello, World!
After