turtle's settiltangle was deprecated in Python 3.1:

"Deprecated since version 3.1."

https://docs.python.org/3.10/library/turtle.html#turtle.settiltangle says of settiltangle:


And the reason:

"`Turtle.tiltangle()` has been enhanced in functionality: it now can be used to get or set the tiltangle. `Turtle.settiltangle()` has been deprecated."

https://docs.python.org/3.10/library/turtle.html#changes-since-python-3-0


However, in docstrings, tiltangle was accidentally marked as deprecated:

"Deprecated since Python 3.1"

https://github.com/python/cpython/blob/v3.10.0/Lib/turtle.py#L2880


Neither tiltangle nor settiltangle raise DeprecationWarnings.


So let's:

* Correct tiltangle's docstring to say it's not really deprecated
* Update settiltangle's docstring to say it is deprecated
* Add a DeprecationWarning to settiltangle
* Internally call self.tiltangle instead of self.settiltangle


BPO references:

2009 https://bugs.python.org/issue5923 - settiltangle originally deprecated, with rationale.

2010 https://bugs.python.org/issue7888 - the mixup was discovered and apparently corrected in py3k and release31-maint. I've not done the SCM archaeology to discover why this regressed.

2020 https://bugs.python.org/issue41165 - both mentioned as deprecated, mixup not noted.