关于PHP中间键的内容解析

$application = function ($names, $a){
    echo "this is a {$names} aaa {$a} application";    
    echo "<br />";
};// 前置中间键$auth = function ($handler){
    return function ($name, $as) use ($handler){
        echo "{$name} need {$as} a auth middleware";        
        echo "<br />";        
        return $handler;
    };
};
$stack = [];// 打包
function pack_middleware($handler, $stack){
    foreach (array_reverse($stack) as $key => $middleware) {        
    $handler = $middleware($handler);
    }    
    return $handler;
}
$stack[&#39;auth&#39;] = $auth;
$run = pack_middleware($application, $stack);
$run(&#39;Laravle&#39;, "aaaaa");

Laravle need aaaaa a auth middleware
this is a a aaa aa application

$a=array("a"=>"Volvo","b"=>"BMW","c"=>"Toyota");
print_r(array_reverse($a));