static void Main(string[] args)
{
Display testDisplay = new Display("iPhone Display", "5'5", "16 million");
Battery testBattery = new Battery("iPhone Battery", "3000mAh", BatteryType.LiIon);
Call callOne = new Call(DateTime.Today, 420);
Call callTwo = new Call(DateTime.Today, 366);
GSM iPhone = new GSM("Apple", "Iphone 7", 499.99m, testDisplay, testBattery);
iPhone.AddCallToCallHistory(callOne);
iPhone.AddCallToCallHistory(callTwo);
iPhone.DisplayInfo();
}