Documentation

https://docs.python.org/3/library/functions.html#slice currently shows:

class slice(start, stop, step=1)

This was changed from slice(start, stop[, step]) in #96579. That default for step is incorrect. It's correct in a range, but in a slice it actually defaults to None:

>>> slice(1,2).step is None
True

Most code handle step=1 and step=None the same way when receiving a slice, but user defined types implementing __getitem__/__setitem__/__delitem__ aren't obliged to, and the correct default should be documented.

Linked PRs

• gh-107755: Document the correct default value of slice step #107756
• [3.12] gh-107755: Document the correct default value of slice step (GH-107756) #108955
• [3.11] gh-107755: Document the correct default value of slice step (GH-107756) #108956