learning scala extracors example

object Twice {
  def apply(x: Int): Int = x *
  def unapply(z: Int): Option[Int] = if (z %  == ) Some(z / ) else None
}

object TwiceTest extends Application {
  val x = Twice()
  x match { case Twice(n) => Console.println(n) } // prints 21
}

object TwiceTest extends Application {
  val x = Twice.apply()
  Twice.unapply(x) match { case Some(n) => Console.println(n) } // prints 21
}