q2_answer.dart

import 'package:http/http.dart' as http;

Future<String> getIdToken({bool? force}) async {
  // fetch update token
  return "abc*******";
}

Future<void> main() async {
  final client = http.Client();
  String token = await getIdToken();
  
  try {
    final response = await client.get(Uri.parse("https://api.***.server"),
        headers: {'Authentication': "Bearer $token", "Access-Control-Allow-Origin": "*"});
    print(response);
    
   if(response.statusCode == 401){
     
     //retry get id token
     token = await getIdToken();
     
     
      final response = await client.get(Uri.parse("https://api.***.server"),
        headers: {'Authentication': "Bearer $token", "Access-Control-Allow-Origin": "*"});
    print(response);
   }
    
  }  on http.ClientException catch ( e) {
   return Future.error(e.message);
  }
}