Should we agree on a style of string formatting?

[AnEnglishmanInNorway]

After my embarrassing round of incorrect string formatting errors in connection with #82, I wondered if we should agree to a consistent way to format strings. With little Python background I located what seems like a decent description of formatting in Python - https://realpython.com/python-f-strings/. Another decent article here: https://www.telerik.com/blogs/string-formatting-python
I think we may already be committed to Python 3, so perhaps f-strings is the way to go now? And perhaps we should get rid of the oldest % formatting in our code?