// DisplayArray - display an array of objects that
        //                implement the IDisplayable interface
        public static void DisplayArray(IDisplayable[] displayables)
        {
            int length = displayables.Length;

            for (int index = 0; index < length; index++)
            {
                IDisplayable displayable = displayables[index];
                Console.WriteLine("{0}", displayable.GetString());
            }
        }