Remove unused imports from the stdlib about cpython

[terryjreedy]

Victor, can this be closed?

[vstinner]

Please keep it open. I would like to visit some options for ssl and ctypes. And check imports in tests.

[vstinner]

The #noqa: F401 comment was discussed in #120421. In short, it's a standard linter command to ignore "imported but unused" warning on the current line.

[encukou]

Could you link to the standard?

[vstinner]

Could you link to the standard?

I don't think that there is a written standard. It's just that multiple linters adopted the same format. Examples:

• Flake8: https://flake8.pycqa.org/en/7.0.0/user/violations.html#in-line-ignoring-errors
• Ruff: https://docs.astral.sh/ruff/linter/#error-suppression
• pycodestyle: https://pycodestyle.pycqa.org/en/latest/intro.html#error-codes
• https://stackoverflow.com/questions/45346575/what-does-noqa-mean-in-python-comments

[encukou]

None of those documents explains what F401 means (though some use it as an example).
So maybe explain it in a comment rather than use a link?

[hugovk]

Flake8 checks lint rules from plugins, each with its own alphabetical prefix. The F codes are from Pyflakes:

F401: module imported but unused

https://flake8.pycqa.org/en/latest/user/error-codes.html#error-violation-codes

In more words in the Ruff docs:

F401 unused-import: {name} imported but unused; consider using importlib.util.find_spec to test for availability

https://docs.astral.sh/ruff/rules/#pyflakes-f

[vstinner]

Ok, I'm now done with my batch of changes to remove unused imports. I close the issue.

If someone wants to automate the detection of unused imports, I suggest to open a new issue. Right now, in total, ruff check|grep F401 returns 173 lines. I didn't add #noqa:F401 to these lines.