[Python-3000] sets in P3K?

[Greg Wilson]

> Terry Reedy:
> Those are my favorites also.  The 2.x -> 3.0 edit of {} to {:} is trivial
> for an auto-correct function.

> Guido Who Needs No Surname:
> That doesn't fix everybody's brain though. Given that sets are much less
> universally useful than dicts I don't think that dict should "give in".

Greg:
I think {:} is more consistent/mnemonic than {} for empty dictionaries
even without sets.