[development doc updates]

[Tim Peters]

[Bengt Richter]
> Nice to have a set type ;-)

Yes, it is!

> Is there an efficient s1==s2 test?

Yes.  It's spelled s1 == s2, BTW (likewise s1 != s2).

> Or should one take that for granted?

No, it takes effort to do that efficiently.  Indeed, "rich comparisons" were
implemented a few releases back in part so that objects *could* do something
extra-efficient for specific comparison operations, and the implementation
of dict comparison was changed soon after to exploit that for "==" and "!=".

> not (s1&s2).issubset(s1|s2) ??

You can if you're crazy <wink>.