public function nthOfQuarter($nth, $dayOfWeek)
{
$dt = $this->copy()->day(1)->month($this->quarter * ChronosInterface::MONTHS_PER_QUARTER);
$lastMonth = $dt->month;
$year = $dt->year;
$dt = $dt->firstOfQuarter()->modify("+{$nth}" . static::$days[$dayOfWeek]);
return $lastMonth < $dt->month || $year !== $dt->year ? false : $dt;
}