Replace Py_NotImplemented returns with the macro form Py_RETURN_NOTIMPLEMENTED.
The macro was introduced in #12724.
diff --git a/Objects/complexobject.c b/Objects/complexobject.c
index 3c6c32a..85c1d22 100644
--- a/Objects/complexobject.c
+++ b/Objects/complexobject.c
@@ -650,8 +650,7 @@
     return res;
 
 Unimplemented:
-    Py_INCREF(Py_NotImplemented);
-    return Py_NotImplemented;
+    Py_RETURN_NOTIMPLEMENTED;
 }
 
 static PyObject *