Untitled

class Car {
  double _speed = 0;

  double get speed => _speed;

  set speed(double value) {
    if (value >= 0) {
      _speed = value;
    } else {
      print("ndak bisa min");
    }
  }
}

void main() {
  var car = Car();
  car.speed = 100;
  print(car.speed);
}