Swift’s type system supports a number of different ways of taking a function or type and abstracting it. Usually, this is done by adding a generic parameter and an associated set of constraints. Similarly, a function that takes a particular type of argument can be abstracted to any number of those arguments by making it variadic with triple-dot (...) syntax. Today, both of these features are permitted separately: you can define a generic function that takes a variable number of arguments, such as
func debugPrint<T>(_ items: T...)
where T: CustomDebugStringConvertible
{
for (item: T) in items {
stdout.write(item.debugDescription)
