Fork

List<Customer> customers = new()
{
  new Customer(1, "Amanda Hugankiss", "Moe's Tavern"),
  new Customer(2, "Hugh Jazz", "Bumtown"),
  new Customer(3, "I.P. Freely", "Bumtown")
};

(IEnumerable<Customer> success, IEnumerable<Customer> failed) = customers.Fork(x => x.Address == "Bumtown");

int successCount = success.Count(); // 2
int failedCount = failed.Count() // 1;