Alexander Belopolsky writes:
Why have builtin sum at all if its use comes with so many caveats?
Because we already have it. If the caveats had been known when it was introduced, maybe it wouldn't have been. The question is whether you can convince python-dev that it's worth changing the definition of sum(). IMO that's going to be very hard to do. All the suggestions I've seen so far are (IMHO, YMMV) just as ugly as the present situation.