fix flake8 config and drop unused code

[wochinge]

Proposed changes:

• drop unused code
• re-configure flake8 to flag unused code / imports

Status (please check what you already did):

• added some tests for the functionality
• updated the documentation
• updated the changelog (please check changelog for instructions)
• reformat files using black (please check Readme for instructions)

[m-vdb]

Do you have an example of how it runs in the CI? I can't find an example of workflow with a failing check. Do we need some sort of documentation to explain what to do if the check fails?

[wochinge]

pushed a commit which triggers a vulture error. Also happy to skip adding vulture to the CI for now. It's not perfect but in my opinion a good start to have a least some check for it.

[m-vdb]

@wochinge it didn't fail because the lint for docstrings failed first :D

I don't think it's a good idea to not add it to the CI, because it will become dead code too (a bit ironic ahah)

[wochinge]

will tackle this separately

[wochinge]

#8490

[wochinge]

I dropped vulture and now use flake8 instead @m-vdb Removed more unused imports - flake8 is a lot better than vulture for this. Dropped vulture since it has too many false positives.

[m-vdb]

but can flake8 detect dead code? unused import are a subset of dead code

[wochinge]

not as good as vulture - but vulture has too many false positives so we can't really run it as part of the CI

[wochinge]

@m-vdb Would be great if we could get this in before my vacation 👀 The review should be quick despite its size as it's just removing dead code.

[m-vdb]

weird because it's used 🤔

[wochinge]

I know - seems to be a false positive. Same as in `visualize - haven't found a way around it unfortunately.

[m-vdb]

⭐ thanks for the quick turnaround!