def is_null(self):
        return self._size == PLP_NULL
Assert that datasets on the state object returned by
dataset/ETHPy150Open denisenkom/pytds/pytds/tds_types.py/PlpReader.is_null--crossover with--dataset/ETHPy150Open ClusterHQ/flocker/flocker/node/agents/test/test_blockdevice.py/assert_discovered_state