public static void Test()
        {
            MobilePhoneDevice telephone = new MobilePhoneDevice("Alcatel", "Lucent");

            telephone.AddCall(new Call(new DateTime(2014, 02, 01, 13, 12, 51), "+359879310320", 354));
            telephone.AddCall(new Call(new DateTime(2014, 02, 02, 17, 21, 50), "0876520320", 211));
            telephone.AddCall(new Call(new DateTime(2014, 02, 03, 10, 45, 13), "0887675685", 108));

            foreach (var call in telephone.CallsHistoryList)
            {
                Console.WriteLine(call);
            }

            var totalCallsPrice = telephone.CalculateTotalPrice(Call.CallPrice);
            Console.WriteLine("The total price of all calls is: {0} BGN.", totalCallsPrice);

            var sortedCallList = telephone.CallsHistoryList.OrderBy(c => c.Duration);
            var longestCall = sortedCallList.Last();
            Console.WriteLine(longestCall);
            telephone.DeleteCall(longestCall);

            var newTotalCallsPrice = telephone.CalculateTotalPrice(Call.CallPrice); // the newly calculated price
            Console.WriteLine("The total price of all calls is after the deletion of the longest call: {0} BGN.", newTotalCallsPrice);

            telephone.ClearCallHistory();
            Console.WriteLine("Here is the call history after the clearing.");

            foreach (var call in telephone.CallsHistoryList)
            {
                Console.WriteLine(call);
            }
        }
        static void Main()
        {
            Battery batteryOne = new Battery(BatteryType.NiMH, 120.00m, 6.00m);
            Display displayOne = new Display(5, 512);
            MobilePhoneDevice mobilePhoneOne = new MobilePhoneDevice("HTC", "HONG ME");  // Task 4 // Task 12
            mobilePhoneOne.battProperty = batteryOne;
            mobilePhoneOne.displProperty = displayOne;

            //Console.Write("Please insert a model: ");
            //mobilePhoneOne.model = Console.ReadLine();
            //Console.Write("Please inser a manufacturer: ");
            //mobilePhoneOne.manufacturer = Console.ReadLine();
            //Console.Write("Please insert a price: ");
            //mobilePhoneOne.price = decimal.Parse(Console.ReadLine());
            //Console.Write("Please insert an owner's name: ");
            //mobilePhoneOne.ownersName = Console.ReadLine();

            Battery batteryTwo = new Battery(BatteryType.LiIon, 96.00m, 5.00m);
            Display displayTwo = new Display(4, 512);
            MobilePhoneDevice mobilePhoneTwo = new MobilePhoneDevice("S Duos", "Samsung", 420.00m, "Georgi Minkov"); // Task 4 // Task 12
            mobilePhoneTwo.battProperty = batteryTwo;
            mobilePhoneTwo.displProperty = displayTwo;

            Battery batteryThree = new Battery(BatteryType.NiCd, 120.00m, 6.00m);
            Display displayThree = new Display(5, 1024);
            MobilePhoneDevice mobilePhoneThree = new MobilePhoneDevice("Lumia", "Nokia", 650.00m, "Dimitar Petrov"); // Task 4 // Task 12
            mobilePhoneThree.battProperty = batteryThree;
            mobilePhoneThree.displProperty = displayThree;

            //Console.WriteLine(mobilePhoneOne); // Task 4
            //Console.WriteLine(mobilePhoneTwo); // Task 4
            //Console.WriteLine(mobilePhoneThree); // Task 4

            MobilePhoneDevice[] mPDArray = { mobilePhoneOne, mobilePhoneTwo, mobilePhoneThree }; // Task 7

            foreach (object item in mPDArray)
            {
                Console.WriteLine(item);
                Console.WriteLine();
            }

            Console.WriteLine(MobilePhoneDevice.IPhone4S);
            Console.WriteLine();
            CallHistoryTest.Test();
        }