python · ambv · Mar 24, 2026 · Oct 17, 2025 · Oct 17, 2025 · Mar 23, 2026
diff --git a/Doc/library/ast.rst b/Doc/library/ast.rst
@@ -131,6 +131,14 @@ Node classes
   Simple indices are represented by their value, extended slices are
   represented as tuples.

+.. versionchanged:: 3.13
+
+    AST node constructors were changed to provide sensible defaults for omitted
+    fields: optional fields now default to ``None``, list fields default to an
+    empty list, and fields of type :class:`!ast.expr_context` default to
+    :class:`Load() <ast.Load>`. Previously, omitted attributes would not exist on constructed
+    nodes (accessing them raised :exc:`AttributeError`).
+
 .. versionchanged:: 3.14

    The :meth:`~object.__repr__` output of :class:`~ast.AST` nodes includes