fun useClosure1(x: Int): (Int) -> Int {
                        // x = 100 のままで使われる.
    val useFun: (Int) -> Int = fun(y: Int) = x + y
    return useFun
}

fun main() {
    val z = useClosure1(100)
    println(z(6))
    println(z(7))
    println(z(8))
}
/*
106
107
108
 */