step - 12

GameRules.kt

private fun rules(first: Throw,
                  second: Throw,
                  block: GameRules.() -> Boolean) =
        GameRules(first, second).run(block)

class GameRules(private val first: Throw,
                private val second: Throw) {
    infix fun Throw.beats(other: Throw) =
            first == this && second == other
}