public static function schedule_sitemap_update_for_year_month_date($date, $time)
{
list($year, $month, $day) = $date;
wp_schedule_single_event($time, 'msm_cron_generate_sitemap_for_year_month_day', array(array('year' => (int) $year, 'month' => (int) $month, 'day' => (int) $day)));
}