protected function get_days() {
        $date = $this->related['type']->timestamp_to_date_array($this->calendar->time);
        $monthdays = $this->related['type']->get_num_days_in_month($date['year'], $date['mon']);

        $days = [];
        for ($dayno = 1; $dayno <= $monthdays; $dayno++) {
            // Get the gregorian representation of the day.
            $timestamp = $this->related['type']->convert_to_timestamp($date['year'], $date['mon'], $dayno);

            $days[] = $this->related['type']->timestamp_to_date_array($timestamp);
        }

        return $days;
    }