step - 6

Throw.kt

interface Throw {
    val winsAgainst: Throw
    fun beats(other: Throw) = other == winsAgainst

    object SCISSORS : Throw {
        override val winsAgainst = PAPER
    }

    object PAPER : Throw {
        override val winsAgainst = ROCK
    }

    object ROCK : Throw {
        override val winsAgainst = SCISSORS
    }
}