#!/usr/local/bin/swift
struct closureA {
    func request(num: Int, response: (a: Int) -> ()) {
        response(num * 10)
    }
}

let a = closureA()
a.request(num: 1) {
    print($0)    // 10
}
a.request(num: 5) {
    print($0)    // 50
}