如何在dart flutter中返回兩個字符串值

我正在做我的flutter項目，我想在那里使用共享引用。查看下面的代碼：

Future<String?> getCredentials() async {
   final localStorage = await SharedPreferences.getInstance();
   final email = localStorage.getString('email');
   final password = localStorage.getString('password');
   return email, password;
}

這是我的getCredentials函數(shù)，我希望此函數(shù)返回電子郵件和密碼作為不同的參數(shù)，但dart不允許我。你能幫我嗎？我該怎么做？

Whole SharedPreference Code:

import 'package:shared_preferences/shared_preferences.dart';

class sharedPreference {
  Future<String?> saveCredentials({
    required String email,
    required String password,
  }) async {
    final localStorage = await SharedPreferences.getInstance();
    await localStorage.setString('email', email);
    await localStorage.setString('password', password);
  }

  Future<String?> getCredentials() async {
    final localStorage = await SharedPreferences.getInstance();
    final email = localStorage.getString('email');
    final password = localStorage.getString('password');
    return email, password;
  }
}