//Inside main.dart
return MaterialApp(
 initialRoute: WelcomeScreen.id,
 routes: {
   WelcomeScreen.id: (context) => WelcomeScreen(),
   LoginScreen.id: (context) => LoginScreen(),
   RegistrationScreen.id: (context) => RegistrationScreen(),
   ChatScreen.id: (context) => ChatScreen(),
 },
);

//Inside **** Class:
static const String id = '****';

//Inside onPressed
  onTap: () => Navigator.pushNamed(context, VideoScreen.id, arguments: {
                'chapter_name': 'Chapter $index',
              }),
              
 // In receiving side
 final  Map<String, String> received = ModalRoute.of(context).settings.arguments;
    final chapterName = received['chapter_name'];