bpo-42317: Improve docs of typing.get_args concerning Union (GH-23254)
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
index 9a993c0..a8de984 100644
--- a/Doc/library/typing.rst
+++ b/Doc/library/typing.rst
@@ -1706,6 +1706,9 @@
For a typing object of the form ``X[Y, Z, ...]`` these functions return
``X`` and ``(Y, Z, ...)``. If ``X`` is a generic alias for a builtin or
:mod:`collections` class, it gets normalized to the original class.
+ If ``X`` is a :class:`Union` contained in another generic type,
+ the order of ``(Y, Z, ...)`` may be different from the order of
+ the original arguments ``[Y, Z, ...]`` due to type caching.
For unsupported objects return ``None`` and ``()`` correspondingly.
Examples::