Fibonacci in PHP using anonymous functions and memoization

gistfile1.php

<?php

$fibMemo = call_user_func(function () {
    $memo = array(0 => 0, 1 => 1);
    $fib = function ($n) use (&$memo, &$fib) {
        if (!isset($memo[$n])) {
            $memo[$n] = $fib($n - 1) + $fib($n - 2);
        }
        return $memo[$n];
    };
    
    return $fib;
});

echo $fibMemo(10);
// >> 55

Awesome!!, it does work, but when does it stop?? Shouldn't be a condition (n<2) return n???, if you put a echo inside the anonymous function you could see that it is doing a doble loop...