+ return Variant::NOTHING;
+}
+
+void
+MidiModel::NoteDiffCommand::change (const NotePtr note,
+ Property prop,
+ const Variant& new_value)
+{
+ assert (note);
+
+ const NoteChange change = {
+ prop, note, 0, get_value(note, prop), new_value
+ };
+
+ if (change.old_value == new_value) {
+ return;
+ }