title: Dynamic fan out with Akka Streams
body: <p>I am building an Akka Streams application that goes through a couple of steps. There is one particular step that produces 0 or more results, it is not known in advance how many there are. Each of the results has to be processed asynchronously (by the same kind of component) and finally all the results have to be merged.</p>
  
  <p>How should I model this in Akka Streams? I noticed that GraphDsl has a Broadcast element that lets you model a fan out, however this seems to be only possible when the number of outlets is know in advance.
  Is there a way in Akka Streams to have something like Broadcast but that fans out to a dynamic number of outlets?</p>