public static void TestHistory()
{
var nokia = new GSM("Nokia", "Lumia920", 500.50, "Gosho",
new Battery("Mistucura-1224fe", 40, 5, BatteryTypes.NiMh), new Display(3.5, ColorDepth._16Bit));
nokia.AddCallHistory(0888124122, 210);
nokia.AddCallHistory(0888124122, 40);
nokia.AddCallHistory(0888124122, 80);
nokia.AddCallHistory(0919125121, 600);
nokia.AddCallHistory(0919125121, 10);
nokia.ShowCalls();
Console.WriteLine("The price of all calls is - {0}", nokia.CalculatePriceForTalk(0.37m));
nokia.RemuveLongestCall();
Console.WriteLine("The price of all calls is - {0}", nokia.CalculatePriceForTalk(0.37m));
nokia.ClearCallHistory();
nokia.ShowCalls();
}