public static void Main()
    {
        Vessel v1 = new Submarine(new NukePlant("Preasureized Water Mk 85"),
                                  new Torpedo("MK 50"), "USS Falls Church");

        v1.LightoffPlant();
        v1.TrainWeapon();
        v1.FireWeapon();
        v1.ShutdownPlant();
    }