sum.kt

/***
 * Sum as an extension function
 ***/

fun List<Int>.sum(): Int {
    var result = 0
    for (i in this) {
        result += i
    }
    return result
}



fun main(args: Array<String>) {
    val l= listOf(1, 2, 3)
    val sum = l.sum()
    println(sum)    // 6
}