How to use the databand.parameters.MonthParameter function in databand

def test_parse(self):
        m = MonthParameter()._p.parse_from_str("2015-04")
        assert m == datetime.date(2015, 4, 1)

def test_serialize(self):
        m = MonthParameter()._p.to_str(datetime.date(2015, 4, 3))
        assert m == "2015-04"

dbnd.Task,
            dbnd.output,
            dbnd.parameter,
            dbnd.data,
            databand.task,
            tasks.DataSourceTask,
            tasks.PipelineTask,
            targets.Target,
            targets.DataTarget,
            dbnd._core.task_build.task_namespace.namespace,
            parameters.Parameter,
            parameters.DateHourParameter,
            parameters.DateMinuteParameter,
            parameters.DateSecondParameter,
            parameters.DateParameter,
            parameters.MonthParameter,
            parameters.YearParameter,
            parameters.DateIntervalParameter,
            parameters.TimeDeltaParameter,
            parameters.IntParameter,
            parameters.FloatParameter,
            parameters.BoolParameter,
        ]
        assert len(expected) > 0

def testSerialize(self):
        date = datetime.date(2013, 2, 3)
        assert parameter[datetime.date]._p.to_str(date) == "2013-02-03"
        assert YearParameter()._p.to_str(date) == "2013"
        assert MonthParameter()._p.to_str(date) == "2013-02"
        dt = datetime.datetime(2013, 2, 3, 4, 5)
        assert parameters.DateHourParameter()._p.to_str(dt) == "2013-02-03T04"

class DateHourTask(TTask):
    dh = parameters.DateHourParameter()


class DateMinuteTask(TTask):
    dm = parameters.DateMinuteParameter()


class DateSecondTask(TTask):
    ds = parameters.DateSecondParameter()


class MonthTask(TTask):
    month = MonthParameter()


class YearTask(TTask):
    year = YearParameter()


class TestDateParameter(object):
    def test_parse(self):
        d = parameter[datetime.date]._p.parse_from_str("2015-04-03")
        assert d == datetime.date(2015, 4, 3)

    def test_serialize(self):
        d = parameter[datetime.date]._p.to_str(datetime.date(2015, 4, 3))
        assert d == "2015-04-03"

    def test_parse_interface(self):