vincenzo@earth:~$ pythonPython 2.5.1 (r251:54863, Oct 5 2007, 13:36:32) [GCC 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)] on linux2Type "help", "copyright", "credits" or "license" for more information.>>> a = [1, 2, 3]>>> a.index(2)1>>> class test:... def __init__(self, a):... self.a = a... >>> list = [test('hello'), test('world')]>>> print list[<__main__.test instance at 0xb7d8ed4c>, <__main__.test instance at 0xb7d8eccc>]>>> list.index(test('hello'))Traceback (most recent call last): File "<stdin>", line 1, in <module>ValueError: list.index(x): x not in list>>>