public function byKey(array $array, int $flags = SORT_REGULAR): array
    {
        ksort($array, $flags);

        foreach ($array as $_key => &$_value) {
            if (is_array($_value)) {
                $_value = $this->byKey($_value, $flags);
            }
        } // unset($_key, $_value); // Housekeeping.

        return $array;
    }