Fat arrow functions usage

fastarrowfunctions.dart

void main() {
  User()
    ..firstName = "Laxman"
    ..lastName = " Bhattarai"
    ..age = 18
    ..printUser();
}

class User {
  String firstName;
  String lastName;
  DateTime birthday;

  String get fullName => firstName + lastName;
  
  set age(int age) =>
      birthday = DateTime.now().subtract(Duration(days: age * 365));
  
  int get age => DateTime.now().year - birthday.year;
  
  bool get isAdult => age >= 18;
  
  printUser() => print(fullName + " is a ${isAdult ? "Adult" : "Child"}");
}