getDates.scala

def getDates(product: String): Future[Either[String, List[LocalDate]]] = product match {
  case "fast" => Future.successful(Right(List(LocalDate.parse("2018-03-09"), LocalDate.parse("2018-03-10"))))
  case "slow" => Future.successful(Right(List(LocalDate.parse("2018-03-07"), LocalDate.parse("2018-03-08"))))
  case "express" => Future.successful(Left("Service not available"))
  case "flash" => Future.failed(new Throwable("haha"))
}