Pythonクイズ

>>> import [1]
>>> class A(object):pass
...
>>> def test(self):
... print "test"
...
>>> a = A()
>>> a.test = [2]
>>> a.test
>
>>> a.test()
test
>>> b = A()
>>> b.test()
Traceback (most recent call last):
File "", line 1, in
AttributeError: 'A' object has no attribute 'test'
>>>

上記を満たすよう[1]、[2]を埋めよ。
追記：
いわゆる特異メソッド