static void Main(string[] args)
{
Dog dog = new Dog("Bao");
Console.WriteLine(dog.ToString());
dog.CelebrateBirthday();
Console.WriteLine(dog.ToString());
Cat cat = new Cat("Miao", 23);
Console.WriteLine(cat.ToString());
cat.CelebrateBirthday();
Console.WriteLine(cat.ToString());
Turtle turtle = new Turtle("Turlo", 2);
Console.WriteLine(turtle.ToString());
turtle.CelebrateBirthday();
Console.WriteLine(turtle.ToString());
}