Dúvida num código de Flutter

Não consigo encontrar o erro neste código de Flutter:

import ‘package:flutter/material.dart’;
import ‘./screens/home.dart’;
import ‘./screens/second.dart’;

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {

@override
Widget build(BuildContext context) {
return new MaterialApp(
title: ‘Navigation’,
routes: <String, WidgetBuilder>{
//All available pages
‘/Home’: (BuildContext context) => new Home(),
‘/Second’: (BuildContext context) => new Second(’’),
},
home: new Home(), //first page displayed
);
}
}