sealed class SomeThing {
  abstract fun run()
  abstract fun play()
}

class Thing1: SomeThing() {
  override fun run() = println("Run Fast!")
  override fun play() = println("Play Hard!")
}
class Thing2: SomeThing() {
  override fun run() = println("Run Silly!")
  override fun play() = println("Play Soft!")
}

class NoThing {} // not part of the sealed class eh? no instantiation for you!