I’d vote #3 as well.

> On Mar 28, 2018, at 11:27 AM, Serhiy Storchaka <storchaka@gmail.com> wrote:
>
> There is a subtle semantic difference between str.format() and "equivalent" f-string.
>
>    '{}{}'.format(a, b)
>    f'{a}{b}'
>
> In most cases this doesn't matter, but when implement the optimization that transforms the former expression to the the latter one ([1], [2]) we have to make a decision what to do with this difference.