def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
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)