>>> class test:
...     _blub = []
...     def __init__ (self):
...             self._blub.append("Hallo")
...             print self._blub
... 
>>> test()
['Hallo']
<__main__.test instance at 0xb7dbdecc>
>>> test()
['Hallo', 'Hallo']
<__main__.test instance at 0xb7dbde0c>
>>> test()
['Hallo', 'Hallo', 'Hallo']
<__main__.test instance at 0xb7dbdecc>