public static function flatten($array)
    {
        $return = [];

        foreach ($array as $key => $value) {
            if (is_array($value)) {
                $return = \array_merge($return, static::flatten($value));
            } elseif ($value instanceof Collection) {
                $return = \array_merge($return, static::flatten($value->all()));
            } else {
                $return[$key] = $value;
            }
        }

        return $return;
    }