gh-126927: Add functools.retry decorator function

[jude253]

I added a retry decorator to functools, written in pure python so it should be maximally portable. I also added unit tests covering all aspects of the functionality. This is something I have been wishing to have for years and I explain in this issue: #126927

It has some keyword arguments that can be configured for different retry behavior and smart defaults.

This is my first contribution to CPython and I would really appreciate any feedback or pointers to add this change.

Tests

• I ran ./python -m unittest Lib/test/test_functools.py -v with no errors
  • I ensured that the new tests I wrote work
• I ran make patchcheck successfully

• Issue: Add retry function to Python standard library #126927

[ghost]

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[terryjreedy]

Closing until issue is re-opened.

[jude253]

Thanks! I will try to gather buy in for this feature at some point. I appreciate the eyes on this!