php 实现一个闭包函数

<?php

function MyClosure(array $prefix)
{
    return function ($_prefix) use ($prefix) {
        if (in_array($_prefix, $prefix)) {
            return "in";
        } else {
            return "not in";
        }
    };
}

$f = MyClosure(array(
    "jpg",
    "png"
));

var_dump($f("jpg"));
var_dump($f("jpgx"));
var_dump($f("png"));