Improve docs of PEP 604 Union (#24301)
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index e36a169..370decc 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -870,19 +870,27 @@
class>`) subclass thereof. If *object* is not
an object of the given type, the function always returns ``False``.
If *classinfo* is a tuple of type objects (or recursively, other such
- tuples), return ``True`` if *object* is an instance of any of the types.
+ tuples) or a :ref:`types-union` of multiple types, return ``True`` if
+ *object* is an instance of any of the types.
If *classinfo* is not a type or tuple of types and such tuples,
a :exc:`TypeError` exception is raised.
+ .. versionchanged:: 3.10
+ *classinfo* can be a :ref:`types-union`.
+
.. function:: issubclass(class, classinfo)
Return ``True`` if *class* is a subclass (direct, indirect or :term:`virtual
<abstract base class>`) of *classinfo*. A
class is considered a subclass of itself. *classinfo* may be a tuple of class
- objects, in which case every entry in *classinfo* will be checked. In any other
+ objects or a :ref:`types-union`, in which case every entry in *classinfo*
+ will be checked. In any other
case, a :exc:`TypeError` exception is raised.
+ .. versionchanged:: 3.10
+ *classinfo* can be a :ref:`types-union`.
+
.. function:: iter(object[, sentinel])