Recursivity with anonymous function

recursivity.php

<?php

namespace Jawira\Tests;

use function sleep;

function write($message): void
{
    echo $message;
}

$countdown = function (int $value, callable $myFn, int $delay = 1) use (&$countdown) {
    $myFn($value);
    sleep($delay);

    return $value > 0 ? $countdown(--$value, $myFn, $delay) : $value;
};

$countdown(10, write::class);