Reduce the number of flake8 errors/warnings

[hey-thanks]

Running flake8 currently causes 200+ errors/warnings to be produced, mostly to do with whitespace and line length. If such an improvement is welcome, I'd be more than happy to submit a PR that improves this situation.

[JessicaTegner]

this is welcome. I've been meaning to add black and flake8 as precommit hooks, for the longest time.

Something like this describes

and of course add it to the ci pipeline

[TheQuinbox]

I'd also recommend adding Isort, to sort your imports.