implements

//implements是对接口的继承
class Test implements InterfaceTest{}

Closure $next

//这是作为参数传入
function test(Closure $next)
{
    $next(123);
    var_dump($next);
}
test(function ($a) {
    echo $a;
});
//这是变量的方法
$closure = function($name){
  　 return sprintf("Hello %s", $name);
}
echo $closure("jerry");// Hello jerry
// 检测$closure变量是否是一个闭包
var_dump($closure instanceof Closure);//true