public static void DoAggregationDemo()
 {
     TransactionManager manager = new TransactionManager();
     double totalAmount = manager.Init()
        .AddTransaction(new Transaction(DateTime.Now, 5000.00D))
        .AddTransaction(new Transaction(new DateTime(2015, 5, 25), 9500))
        .AddTransaction(new Transaction(new DateTime(2015, 11, 18), 11000.52D)).GetTotalAmount();
     Console.WriteLine("The aggregated amount is " + totalAmount);
 }
        public static void DoDemoWithAggregate()
        {
            TransactionManager manager = new TransactionManager();
            manager.Init()
              .AddTransaction(new Transaction(DateTime.Now, 5000.00D))
              .AddTransaction(new Transaction(new DateTime(2015, 5, 25), 9500))
              .AddTransaction(new Transaction(new DateTime(2015, 11, 18), 11000.52D));

            double totalAmount = manager.Transactions.Aggregate(0.0D, (d, t) => d + t.Amount);
            Console.WriteLine("The aggregated amount (with Aggregate ) is " + totalAmount);
        }