Describe the issue linked to the documentation

In the Contributing code section of the Contributing page, it is stated that:

5. Make sure that your PR does not add PEP8 violations. On a Unix-like system, you can run make flake8-diff. flake8 path_to_file, would work for any system, but please avoid reformatting parts of the file that your pull request doesn’t change, as it distracts from code review.

I've never been able to run the make flake8-diff command on MacOS. Does it require to install the flake8-diff Python package? The documentation of flake8 states that one can use the following command:

$ git diff -u | flake8 --diff

which works for me.

So I'm maybe asking a dumb question but what are the core devs using currently?