'Notifies partner_to that a message (not stored in DB) has been
written in this channel'

def _send_transient_message(self, partner_to, content):

    self.env['bus.bus'].sendone((self._cr.dbname, 'res.partner', partner_to.id), {'body': (("<span    class='o_mail_notification'>" + content) + '</span>'), 'channel_ids': [self.id], 'info': 'transient_message'})
