It's implemented in 3.11. Documentation still hasn't been written for it yet though and that's why the issue is still open, https://github.com/python/cpython/is

It's implemented in 3.11. Documentation still hasn't been written for it yet though and that's why the issue is still open, https://github.com/python/cpython/issues/90908 https://github.com/python/cpython/issues/90908.