def save_last_sync(self, ids, process):
        try:
            spec = {'_id': 'last_sync'}
            document = {'$set': {process: ids}}
            self.db.internal.update(spec, document, upsert=True)
        except Exception as e:
            raise DatabaseException(e)
def __init__(self, root, transforms=None):

        super().__init__(root=root)
        self.transforms = transforms

        self._flow_list = []
        self._image_list = []