diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst index 2bdfb337f02056..bb88cf73ec1e89 100644 --- a/Doc/library/sys.rst +++ b/Doc/library/sys.rst @@ -1247,6 +1247,9 @@ always available. Unless explicitly noted otherwise, all variables are read-only .. versionadded:: 3.13 + .. impl-detail:: + + It is not guaranteed to exist in all implementations of Python. .. function:: is_finalizing()