Equivalent of std::set

[Nicolas Fleury]

Hi,

I haven't work so much in python and I was wondering what python 
programmers use for string collections, like an equivalent of C++ 
std::set.  Do you use a dictionary with dummy values?  Tuple/list?  Is 
there any other structure in some module with uniqueness ensured and 
lookup optimised?  I'm only interested in storing strings in that structure.

Thx for help

Nicolas