[Shi] > Yes, i am using python 2.3, > I have used from sets import * > but still report the same error: > > > Traceback (most recent call last): > > > File "<interactive input>", line 1, in ? > > > NameError: name 'set' is not defined It's 'Set', not 'set'. Try this: >>> import sets >>> dir(sets) -- Richie Hindle richie at entrian.com