The Simplest Implementation of a PHP Stack

stack.class.php

class stack {

    private $arr = array();

    public function push($s) {
        $this->arr[] = $s;
    }    

    public function pop() {
        return array_pop($this->arr);
    }

    public function peek() {
        return end(array_values($this->arr));
    }

    public function isempty() {
        return empty($this->arr);
    }

}

Hi,
I think that
return end(array_values($this->arr));
should be fixed to
end($this->arr);