def insert(self, doc, synced=False):
        doc.id = self.get_next_id()
        doc.synced = synced
        try:
            self.db.docs.insert(doc)
        except Exception as e:
            raise DatabaseException(e)
        return doc
def applies(cls, obj):
        if not cls.loaded():
            return False
        import cudf
        return isinstance(obj, (cudf.DataFrame, cudf.Series))