It already seems to pass mypy. I wonder what changed, given that it was
on the exclusion list. So this commit consists of me ensuring
`--disallow-untyped-defs` passes and a minor fixup to a function that
returned either `True` or `None`.
Part of #9744
Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.
`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>`
- Update black version to the latest
- Run black auto formatting over the codebase
- Run autoformatting according to [`docs/code_style.md
`](80d6dc9783/docs/code_style.md)
- Update `code_style.md` docs around installing black to use the correct version
