def test_excluding(self):

        dtr = DatetimeRange(self.dt1, self.dt2, self.delta)
        excludes = [
            datetime(2015, 3, 2, 4, 30), 
            datetime(2015, 3, 3, 16, 30)
        ]
        dates = [d for d in dtr.excluding(excludes)]
        self.assertEqual(dates, [
            datetime(2015, 3, 1, 16, 30),
            datetime(2015, 3, 2, 16, 30),
            datetime(2015, 3, 3, 4, 30),
            datetime(2015, 3, 4, 4, 30)
        ])