public static double GetAvgAge(Animal[] animal)
        {
            double avgAge = 0;
            int currentSum = 0;
            for (int i = 0; i < animal.Length; i++)
            {
                currentSum += animal[i].Age;
            }
            avgAge = (double)currentSum/animal.Length;

            return avgAge;
        }
 public static void GetAnimalBySound(Animal animal)
 {
     Console.WriteLine("{0} is: {1}",animal.Name,animal.GetType().Name);
 }