def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def testDeviceWrapperSerialization(self):
    wrapper_cls = rnn_cell_wrapper_v2.DeviceWrapper
    cell = layers.LSTMCell(10)
    wrapper = wrapper_cls(cell, "/cpu:0")
    config = wrapper.get_config()

    reconstructed_wrapper = wrapper_cls.from_config(config)
    self.assertDictEqual(config, reconstructed_wrapper.get_config())
    self.assertIsInstance(reconstructed_wrapper, wrapper_cls)