"Given a [[stream|iterables]] whose elements are also streams, return a new stream with all elements of every nested stream. If there are no nested streams, or if all of the nested streams are empty, return an empty stream. For example, the expression expand { 1..3, {5}, \"hi\" } results in the stream `{ 1, 2, 3, 5, 'h', 'i' }` which has the type `{Integer|Character*}`." see (`function Iterable.flatMap`, `function concatenate`, `function Iterable.chain`) tagged("Streams") since("1.1.0") shared Iterable<Element,OuterAbsent|InnerAbsent> expand<Element,OuterAbsent,InnerAbsent> (Iterable<Iterable<Element,InnerAbsent>,OuterAbsent> iterables) given OuterAbsent satisfies Null given InnerAbsent satisfies Null => { for (it in iterables) for (val in it) val };