For py3 it does not matter, but on py2 %s prettifies result a bit:

    kirr@deca:~$ python
    Python 2.7.18 (default, Jul 14 2021, 08:11:37)
    >>> str(0.1-0.01)
    '0.09'
    >>> repr(0.1-0.01)
    '0.09000000000000001'

    kirr@deca:~$ python3
    Python 3.9.2 (default, Feb 28 2021, 17:03:44)
    >>> str(0.1-0.01)
    '0.09000000000000001'
    >>> repr(0.1-0.01)
    '0.09000000000000001'

Should make the diff in between master and py2 a bit smaller.