如何才能获得测试Kotlin中函数性能所需的时间

mixAnimalsA

fun mixAnimalsA(a1: Animal, a2: Animal) =
        when (setOf(a1, a2)) {
            setOf(Animal.OWL, Animal.Leopard) -> Beast.OWLPARD
            setOf(Animal.ELEPHANT, Animal.BUTTERFLY) -> Beast.BUTTERPHANT
            else -> throw Exception("Not possible combination")
        }

mixAnimalsB

fun mixAnimalsB(a1: Animal, a2: Animal) =
        when (setOf(a1, a2)) {
            (c1 == Animal.OWL && c2 == Animal.Leopard) ||
                    (c2 == Animal.OWL && c1 == Animal.Leopard) -> Beast.OWLPARD
            (c1 == Animal.ELEPHANT && c2 == Animal.BUTTERFLY) ||
                    (c2 == Animal.ELEPHANT && c1 == Animal.BUTTERFLY)-> Beast.BUTTERPHANT
            else -> throw Exception("Not possible combination")
        }

动物和野兽是枚举.如何衡量每个函数运行的时间？

val time = measureTimeMillis {
    // call your function here
}

它们分别以毫秒和纳秒返回测量的时间.