public void ExampleModification() { var customers = new CustomerGenerator().Generate(5); var customersWithOneExtraAtBeginning = customers.Prepend(new Customer() { Id = 0 }); var customersWithOneExtraAtEnd = customers.Append(new Customer() { Id = 99 }); var allFiveCustomers = customers.DefaultIfEmpty(); var emptyCustomersArray = new Customer[0]; var containsNullCustomer = emptyCustomersArray.DefaultIfEmpty(); var containsOneDefaultCustomer = emptyCustomersArray.DefaultIfEmpty(new Customer()); }