Validar RUT en Kotlin. Yes, very cool code.

RUT.kt

class RUT {
    companion object {
        fun validateRUT(rut : String) : Boolean {
            if (!rut.matches(Regex("[0-9]{1,2}(.?[0-9]{3}){2}-?[0-9kK]"))) {
                return false
            }

            // Very cool code :-)
            val rutf = rut.toLowerCase().replace(Regex("[-.]"), "")
            val rutl = rutf.takeLast(1); var sum = 0; var i = 0
            for (x in rutf.dropLast(1).reversed()){
                sum += (x.toString().toInt() * ((i % 6) + 2)); i+=1
            }

            val div = 11 - (sum % 11)
            return (if (div == 11) 0 else div) == (if (rutl == "k") 10 else rutl.toInt())
        }
    }
}