LastDemo.cs

private static void LastDemo(List<Order> orders)
{
    var lastOrderAfterMarch = orders.Last(order => order.OrderDate >= march);
    PrintHeaderFooter("Last order after March", () => PrintOrder(lastOrderAfterMarch, indentBy), indentBy);

    var LastOrderAfterSeptember = orders.LastOrDefault(order => order.OrderDate >= september);
    PrintHeaderFooter("Last or Default order after September", () => PrintOrder(LastOrderAfterSeptember, indentBy), indentBy);
}