如何在dart中使用firebase转诊系统？

dependencies:
  firebase_core: ^1.0.0
  cloud_firestore: ^2.0.0

import 'package:firebase_core/firebase_core.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  // 初始化Firebase
  runApp(MyApp());
}

import 'package:cloud_firestore/cloud_firestore.dart';

final CollectionReference referralCollection = FirebaseFirestore.instance.collection('referrals');

// 添加转诊
Future<void> addReferral(String patientName, String doctorName) {
  return referralCollection.add({
    'patientName': patientName,
    'doctorName': doctorName,
  });
}

// 查询转诊
Stream<QuerySnapshot> getReferrals() {
  return referralCollection.snapshots();
}