Source.zipWithN
Combine the elements of multiple streams into a stream of sequences using a combiner function.
Signature
def zipWithN[T, O](zipper: immutable.Seq[T] => O)(sources: immutable.Seq[Source[T, _]]): Source[O, NotUsed]
Description
Combine the elements of multiple streams into a stream of sequences using a combiner function.
emits when all of the inputs has an element available
completes when any upstream completes