Scala product function to generate combinations across sets.

product.scala

 def product[T](seqs: Seq[Seq[T]]): Seq[Seq[T]] = {
    var combos = Seq[Seq[T]](Seq[T]())
    for (seq <- seqs) {
      combos = for {
        combo <- combos
        id <- seq
      } yield combo :+ id
    }
    combos
  }