public function hasKey(string $needle, array $haystack) : bool
    {
        foreach ($haystack as $key => $value) {
            if ($key === $needle) {
                return true;
            }

            if (is_array($value)) {
                if ($x = $this->hasKey($needle, $value)) {
                    return $x;
                }
            }
        }

        return false;
    }