Are there any "correct" implementations of tzinfo?

[random832 at fastmail.us]

On Sat, Sep 12, 2015, at 14:36, Carl Meyer wrote:
> Well, the problem is that because datetime doesn't include any way to
> disambiguate ambiguous times, it's not really possible to implement
> complex timezones in a way that is both correct (if your definition of
> correct includes "timezone conversions are lossless") and also matches
> the intended model of datetime.

I'm not even talking about ambiguous times. I'm mostly talking about
unambiguous times on opposite sides of the transition. It's not even
clear to me how the model of datetime envisions _those_ working with
"classic arithmetic".