Add Py_RETURN_NOTIMPLEMENTED macro. Fixes #12724.
diff --git a/Include/object.h b/Include/object.h
index 3753785..e0c68c1 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -792,6 +792,10 @@
 PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
 #define Py_NotImplemented (&_Py_NotImplementedStruct)
 
+/* Macro for returning Py_NotImplemented from a function */
+#define Py_RETURN_NOTIMPLEMENTED \
+    return Py_INCREF(Py_NotImplemented), Py_NotImplemented
+
 /* Rich comparison opcodes */
 #define Py_LT 0
 #define Py_LE 1