Array Merge with Integer Keys

ArrayMergeUtil.php

class ArrayMergeUtil
{
    /**
     * @param array $array
     *
     * @return array
     */
    public static function flatArrayAndSumValues(array $array)
    {
        $result = [];
        foreach ($array as $key => $row) {
            if (is_array($row)) {
                $result[$key] = array_sum($row);
            } else {
                $result[$key] = $row;
            }
        }
        arsort($result);

        return $result;
    }

    /**
     * @param $array
     * @return array
     */
    function prefixer($array)
    {
        $out = array();
        foreach ($array as $k => $v) {
            $out['_' . $k] = $v;
        }
        return $out;
    }

    /**
     * @param $array
     * @return array
     */
    function unprefixer($array)
    {
        $out = array();
        foreach ($array as $k => $v) {
            $newkey = substr($k, 1);
            $out[$newkey] = $v;
        }
        return $out;
    }

    /**
     * @param $a
     * @param $b
     * @return array
     */
    function array_merge_recursive_improved($a, $b)
    {
        $a = $this->prefixer($a);
        $b = $this->prefixer($b);
        $out = $this->unprefixer(array_merge_recursive($a, $b));
        return $out;
    }
}