Add code formatting to Python files? (at least examples/case.py?)

[sbryngelson]

It seems like some of our examples case.py files have strange formatting. This is probably, in part, a space/tab issue, though it is also inconsistent across different examples. This could easily be fixed by enforcing some sort of formatting for all Python files, or at least ones in examples/.

Black would do the trick (I tried it locally, and it looks consistent and "normal"). This could be integrated into CI just as ./mfc.sh lint (or perhaps as part of ./mfc.sh format).