decorator test.py

# define decorator
def my_deco(*arg, **kwargs):
  def _(func):
    func.__dict__.setdefault('foo', (arg, kwargs))
    return func
  return _

# make decorated function
@my_deco(alice='brother')
def echo(msg):
  print msg

# test
assert(echo.__dict__['foo'] == ((), {'alice': 'brother'}))