public function int(int $min = null, int $max = null)   // inclusive max and min
    {
        $array = [];
        return $this->closure_array_walk(function ($key) use (&$array, $min, $max) {
            if (($key = (int)$key) === false) {
                return $array[] = false;
            }
            if ($max !== null) {
                $key = ($key <= $max ? $key : false);
            }
            if ($min !== null) {
                $key = ($key >= $min ? $key : false);
            }
            return $array[] = $key;
        })($array);
    }