def fetch(id: String): Future[Option[Record]] = Future {
    Thread sleep 100
    if (id != "b" && id != "d") {
        Some(Record(id))
    } else None
}

def fetchRecordDetail(record: Record): Future[RecordDetail] = Future {
    Thread sleep 100
    RecordDetail(record.id + "_detail")
}

def upload(recordDetail: RecordDetail): Future[UploadResult] = Future {
    Thread sleep 100
    UploadResult(recordDetail.id + "_uploaded")
}

def notifyUploaded(results: Seq[UploadResult]): Future[Unit] = Future{ println("notified " + results)}

   val result: Future[Unit] = //Final call to 'notifyUploaded' goes here

    Await.ready(result, Duration.Inf)

val ids: Seq[String] = Seq("a", "b", "c", "d")
def filterSome(s:String) = fetch(s) map ((s, _)) collect { case (s, Some(v)) => v }
val validData = ids map filterSome
Await.ready(Future.sequence(validData), Duration.Inf)
val records = validData.map(_.value.get.toOption)
val recordDetails = records.flatten map fetchRecordDetail
Await.ready(Future.sequence(recordDetails), Duration.Inf)
val uploadResult = recordDetails.map(_.value.get.toOption).flatten  map upload
Await.ready(Future.sequence(uploadResult), Duration.Inf)
val seqUploadResult = uploadResult.map(_.value.get.toOption)
val result: Future[Unit] =  notifyUploaded(seqUploadResult.flatten)
Await.ready(result, Duration.Inf)