void main() {
  Car myCar = Car();
  print(myCar.numberOfSeat);
  myCar.drive();

  ElectriCar myTesla = ElectriCar();
  myTesla.drive();
  print(myTesla.batteryLevel);

}

class Car {
  int numberOfSeat = 5;

  void drive() {
    print('wheel turn');
  }
}

class ElectriCar extends Car {
  int batteryLevel = 100;
  void recharge() {
    batteryLevel = 100;
  }
}