def getall(self):
        try:
            spec = {'data': {'$exists': 1}}
            fields = {'_id': 0}
            sort = [('tid', 1)]
            cur = self.db.docs.find(spec, fields, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        return [Document(**row) for row in cur]
def __init__(self, masked_tokens=None, name='num_tokens', dtype=tf.int64):
    self._masked_tokens = masked_tokens or []
    super().__init__(name, dtype)