import 'package:flutter/foundation.dart'; mixin StatusNotifierMixin on ChangeNotifier { ValueChanged? _statusListener; void addStatusListener(ValueChanged listener) { _statusListener = listener; } void clearStatusListener() { _statusListener = null; } @override void notifyListeners({T? status}) { super.notifyListeners(); if (status != null) { _statusListener?.call(status); } } }