class Foo(object):
  def __init__(self,arg):
    """docstring for __init__"""
    self.arg = arg

  def dec(fn):
    def wrapper(*args):
      # args[0] is self. Lame
      args[0].arg = 'not what you thought, huh?'
      return fn(*args)
    return wrapper


  @dec
  def bar(self):
    """docstring for bar"""
    return self.arg