[Python-ideas] Implement __add__ for set and frozenset

[Greg Ewing]

Brandon Mintern wrote:
> Intuitively, it
> _shouldn't_ matter what order the arguments are in. What is the
> meaning of taking the set-difference of a bunch of sets? Should we
> promote an operation that doesn't make any sense?

Taking a lead from mathematics here, there are symbols for the
sum and product of a sequence (big-sigma and big-pi) but not
difference or quotient, for similar reasons.

-- 
Greg