Add doc for Py_RETURN_NOTIMPLEMENTED, added in #12724.
diff --git a/Doc/c-api/object.rst b/Doc/c-api/object.rst
index d0d45ad..88ba5ac 100644
--- a/Doc/c-api/object.rst
+++ b/Doc/c-api/object.rst
@@ -6,6 +6,19 @@
===============
+.. c:var:: PyObject* Py_NotImplemented
+
+ The ``NotImplemented`` singleton, used to signal that an operation is
+ not implemented for the given type combination.
+
+
+.. c:macro:: Py_RETURN_NOTIMPLEMENTED
+
+ Properly handle returning :c:data:`Py_NotImplemented` from within a C
+ function (that is, increment the reference count of NotImplemented and
+ return it).
+
+
.. c:function:: int PyObject_Print(PyObject *o, FILE *fp, int flags)
Print an object *o*, on file *fp*. Returns ``-1`` on error. The flags argument