package foo

fun Int.sum0(other: Int): Int = this + other

fun box(): String {
    fun Int.sum1(other: Int): Int = this + other

    val sum2 = fun Int.(other: Int): Int = this + other

    var x = 10
    x = x.sum0(5)
    x = x.sum1(5)
    x = x.sum2(5)

    var y = 10
    y = (Int::sum0)(y, 5)
    y = (Int::sum1)(y, 5)
    y = y.sum2(5)

    var result:String = (if (x == y && x == 25) "OK" else "x=${x} y=${y}")
    return result
}
