Using 'line-length=80' and flake8-bugbear's B950 warning, I respect
black's formatting of 88 columns max.
The T4 category is related to mypy lints, using the 'flake8-mypy`
plugin.
The max complexity is supposed to make you write shorter functions with
less complexity, using the cyclomatic complexity heuristic.
This file is almost directly taken from black's own flake8
configuration, because I'm using it as a linter and I mostly agreed with
its settings.
