Untitled

class Car {
  int _speed = 0;

  int get speed => _speed;

  set speed(int value) {
    if (value >= 0) {
      _speed = value;
    } else {
      print('Speed cannot be negative');
    }
  }
}

void main() {
  Car car = Car();
  car.speed = 30;
  print('Speed: ${car.speed}');

  car.speed = -10;
  print('Speed: ${car.speed}');
}