gistfile1.txt

> cat test.py
from contextlib import contextmanager

@contextmanager
def polite():
    print("Hi!")
    yield
    print("Bye!")

@polite
def fun():
    pass

> python3 test.py
Traceback (most recent call last):
  File "test.py", line 9, in <module>
    @polite
  File "/usr/lib/python3.3/contextlib.py", line 115, in helper
    return _GeneratorContextManager(func, *args, **kwds)
  File "/usr/lib/python3.3/contextlib.py", line 37, in __init__
    self.gen = func(*args, **kwds)
TypeError: polite() takes 0 positional arguments but 1 was given