Oh, right! We can do something like:
```
val f = sentinelClients.map(_.getMasterAddr(master))
val ff = Future.find(f) { case Some(x) => true case _ => false }
               .map {
                      case Some(Some((ip: String, port: Int))) => initFunction(ip, port)
                      case _ => throw new Exception(s"No such master '$master'")
                    }

Await.result(ff, 15 seconds)
```