'Creates a group.
:param context: the context of the caller.
:param group: the group object.
:returns: model_update'

def create_group(self, context, group):

    LOG.debug('Creating    group.')
    model_update = {'status': fields.GroupStatus.AVAILABLE}
    for vol_type_id in group.volume_type_ids:
        replication_type = self._get_volume_replicated_type(context, None, vol_type_id)
        if replication_type:
            LOG.error('Unable    to    create    group:    create    group    with    replication    volume    type    is    not    supported.')
            model_update = {'status': fields.GroupStatus.ERROR}
            return model_update
    if utils.is_group_a_cg_snapshot_type(group):
        return {'status': fields.GroupStatus.AVAILABLE}
    raise NotImplementedError()
