def validAge(s: String): Validation[List[String], Int] =
    try {
      val a = s.toInt
      if(a < 0)
        Failure(List("Age must be greater than 0"))
      else if(a > 130)
        Failure(List("Age must be less than 130"))
      else
        Success(a)
    } catch {
      case e => Failure(List(e.toString))
    }