Dart async/await operation

asynco.dart

void main(){
  results();
}

void results()async{
  await printNumber("A",100);
   printNumber("B",200);
}

Future<void> printNumber(var a,int delay)async{
  for(int i=0;i<5;i++){
    await Future.delayed(Duration(milliseconds: delay));
    print("$a -> $i");
  }
}