function unsubscribeEmails($topics_ids, $emails)
 {
     if (!is_array($emails)) {
         $emails = array($emails);
     }
     $n = sizeof($emails);
     for ($i = 0; $i < $n; $i += MAX_EMAILS_AT_ONCE) {
         $_emails = array_slice($emails, $i, MAX_EMAILS_AT_ONCE);
         Subscriptions::_unsubscribeEmails($topics_ids, $_emails);
     }
 }