'Set group_access for the specified item to the specified group
ids within the content partition.'

def set_group_access(self, item_location, group_ids, partition_id=None):

    item = self.store.get_item(item_location)
    item.group_access[(self.content_partition.id if (partition_id is None) else partition_id)] = group_ids
    self.store.update_item(item, self.user.id)
