`groupedCollect` helper method for parallelism

groupedCollect.scala

object future {
  def groupedCollect[A, B](xs: Seq[A], par: Int)(f: A => Future[B]): Future[Seq[B]] = {
    val bsF: Future[Seq[B]] = Future.value(Seq.empty[B])
    xs.grouped(par).foldLeft(bsF){ case (bsF, group) => {
      for {
        bs <- bsF
        xs <- Future.collect(group.map(f))
      } yield bs ++ xs
    }}
  }
}