Flutter如何停止监听单个firestore文档文件(flutter 2.2空安全)

import 'package:cloud_firestore/cloud_firestore.dart';

// 创建Firestore实例
final FirebaseFirestore firestore = FirebaseFirestore.instance;

// 获取要监听的文档引用
final DocumentReference documentRef = firestore.collection('collectionName').doc('documentId');

// 开始监听文档变化
StreamSubscription<DocumentSnapshot> subscription = documentRef.snapshots().listen((snapshot) {
  // 处理文档变化
  // ...
});

// 停止监听
subscription.cancel();