public static void Polymorphism()
{
Animal animal = new Animal();
Bird bird = new Bird();
Dog spot = new Dog();
Cat fluffy = new Cat();
animal = spot;
animal.Speak(); //Woof!
(animal as Dog).Speak(); //Woof!
/*
* dog = animal;
*
* dog = animal as Dog;
*/
Vet v = new Vet();
v.Heal(spot);
v.Heal(bird);
v.Heal(animal);
}