Implement string formatting

[rochacbruno]

This joke can be really useful if implements this

a = '12'
b = 2.7182
lst = f['{a:d}',  '{b:.3f}']
12, 2.718

The way I found to implement this is getting all sttring occurences in the args and pass it through .format passing the globals dictionary.

[Carreau]

Arguably that should be f[f'{a:d}', f'{b:.3f}'] no? You can also inspect.get_frames() and look up to have it work in local scopes I guess. Happy to get that in if you think it is useful. Though if we go that route we'll have to ass some tests and documentation 😆