public function plusHours(int $hours) : LocalTime
    {
        if ($hours === 0) {
            return $this;
        }

        $hour = (($hours % self::HOURS_PER_DAY) + $this->hour + self::HOURS_PER_DAY) % self::HOURS_PER_DAY;

        return new LocalTime($hour, $this->minute, $this->second, $this->nano);
    }