DOC: Style format
- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Can you fix up merge conflict? @WillAyd I can't resolve this conflict, And now it's saying that I changed 150 files (no clue).

I think I will close this PR and open another one with the exact changes.