Robot.kt

interface Robot {
    fun reset()
    fun fly()
    fun talk()
}

class ButterflyRobot : Robot {
 
    override fun reset() {
        TODO("not implemented")
    }

    override fun fly() {
        TODO("not implemented")
    }

    override fun talk() {
        // a method that we are not going to use.
        TODO("???")
    }
}