如何在flutter中创建自定义堆栈？

import 'package:flutter/material.dart';

class CustomStack extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        // 在这里添加子组件
      ],
    );
  }
}

class CustomStack extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        Positioned(
          top: 0,
          left: 0,
          child: Container(
            width: 100,
            height: 100,
            color: Colors.red,
          ),
        ),
        Positioned(
          top: 50,
          left: 50,
          child: Container(
            width: 100,
            height: 100,
            color: Colors.blue,
          ),
        ),
      ],
    );
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Custom Stack'),
        ),
        body: Center(
          child: CustomStack(),
        ),
      ),
    );
  }
}