Replace Py_NotImplemented returns with the macro form Py_RETURN_NOTIMPLEMENTED.
The macro was introduced in #12724.
diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index db5c17e..3f77718 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -402,8 +402,7 @@
     if ((op != Py_EQ && op != Py_NE) ||
         !PyCode_Check(self) ||
         !PyCode_Check(other)) {
-        Py_INCREF(Py_NotImplemented);
-        return Py_NotImplemented;
+        Py_RETURN_NOTIMPLEMENTED;
     }
 
     co = (PyCodeObject *)self;