"""

        from kallithea.lib.celerylib import tasks, run_task

        if recipients and not getattr(recipients, '__iter__', False):

            raise Exception('recipients must be a list or iterable')

        created_by_obj = self._get_user(created_by)

        recipients_objs = []

        if recipients:

            for u in recipients:

                obj = self._get_user(u)

                if obj:

                    recipients_objs.append(obj)

                else:

                    # TODO: inform user that requested operation couldn't be completed

                    log.error('cannot email unknown user %r', u)

            recipients_objs = set(recipients_objs)

            log.debug('sending notifications %s to %s' % (

                type_, recipients_objs)

            )

        elif recipients is None:

            # empty recipients means to all admins

            recipients_objs = User.query().filter(User.admin == True).all()

            log.debug('sending notifications %s to admins: %s' % (

                type_, recipients_objs)

            )

        #else: silently skip notification mails?

        # TODO: inform user who are notified

        notif = Notification.create(

            created_by=created_by_obj, subject=subject,

            body=body, recipients=recipients_objs, type_=type_

        )

        if not with_email:

            return notif

        #don't send email to person who created this comment

        rec_objs = set(recipients_objs).difference(set([created_by_obj]))

        headers = None

        if 'threading' in email_kwargs:

            headers = {'References': ' '.join('<%s>' % x for x in email_kwargs['threading'])}

        # send email with notification to all other participants

        for rec in rec_objs:

            ## this is passed into template

                      'body': h.rst_w_mentions(body),

                      'when': h.fmt_date(notif.created_on),

                      'user': notif.created_by_user.username,

                      }

            email_subject = EmailNotificationModel()\

            email_txt_body = EmailNotificationModel()\

            email_html_body = EmailNotificationModel()\

            run_task(tasks.send_email, [rec.email], email_subject, email_txt_body,

                     email_html_body, headers)

        return notif

    def delete(self, user, notification):

        # we don't want to remove actual notification just the assignment

        try:

            notification = self.__get_notification(notification)

            user = self._get_user(user)

            if notification and user:

                obj = UserNotification.query()\

                        .filter(UserNotification.user == user)\

                        .filter(UserNotification.notification

                                == notification)\

                        .one()

                Session().delete(obj)

                return True

        except Exception:

            log.error(traceback.format_exc())

            raise

    def get_for_user(self, user, filter_=None):

        """

        Get notifications for given user, filter them if filter dict is given

        :param user:

        :param filter:

        """

        user = self._get_user(user)

        q = UserNotification.query()\

            .filter(UserNotification.user == user)\

            .join((Notification, UserNotification.notification_id ==

                                 Notification.notification_id))\

            .options(joinedload('notification'))\

            .options(subqueryload('notification.created_by_user'))\

            .order_by(Notification.created_on.desc())

        if filter_:

            q = q.filter(Notification.type_.in_(filter_))

        return q.all()

    def mark_read(self, user, notification):

        try:

            notification = self.__get_notification(notification)