public function normalized() : Period
    {
        $totalMonths = $this->years * LocalTime::MONTHS_PER_YEAR + $this->months;

        $splitYears = \intdiv($totalMonths, 12);
        $splitMonths = $totalMonths % 12;

        if ($splitYears === $this->years || $splitMonths === $this->months) {
            return $this;
        }

        return new Period($splitYears, $splitMonths, $this->days);
    }