如何在flutter中将全选和全选按钮添加到以下代码中？

import 'package:flutter/material.dart';

class MyCheckboxList extends StatefulWidget {
  @override
  _MyCheckboxListState createState() => _MyCheckboxListState();
}

class _MyCheckboxListState extends State<MyCheckboxList> {
  List<bool> checkedList = List.generate(5, (index) => false);

  bool isAllChecked = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Checkbox List'),
      ),
      body: Column(
        children: [
          ListTile(
            title: Text('全选'),
            leading: Checkbox(
              value: isAllChecked,
              onChanged: (value) {
                setState(() {
                  isAllChecked = value;
                  checkedList = List.generate(5, (index) => value);
                });
              },
            ),
          ),
          Expanded(
            child: ListView.builder(
              itemCount: 5,
              itemBuilder: (context, index) {
                return ListTile(
                  title: Text('Item ${index + 1}'),
                  leading: Checkbox(
                    value: checkedList[index],
                    onChanged: (value) {
                      setState(() {
                        checkedList[index] = value;
                        isAllChecked = checkedList.every((value) => value);
                      });
                    },
                  ),
                );
              },
            ),
          ),
        ],
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyCheckboxList(),
  ));
}