return dict of lists  rez[(<org_id>, <service_id>)] = [(channel_id, channel_info)]

def _get_all_initialized_channels(self):
        """ return dict of lists  rez[(<org_id>, <service_id>)] = [(channel_id, channel_info)] """
        channels_dict = defaultdict(list)
        for service_base_dir in self._get_persistent_mpe_dir().glob("*/*"):
            org_id     = service_base_dir.parent.name
            service_id = service_base_dir.name
            channels   = self._get_initialized_channels_for_service(org_id, service_id)
            if (channels):
                channels_dict[(org_id, service_id)] = channels
        return channels_dict