def test_cf_timedelta(self):
        examples = [
            ('1D', 'days', np.int64(1)),
            (['1D', '2D', '3D'], 'days', np.array([1, 2, 3], 'int64')),
            ('1h', 'hours', np.int64(1)),
            ('1ms', 'milliseconds', np.int64(1)),
            ('1us', 'microseconds', np.int64(1)),
            (['NaT', '0s', '1s'], None, [np.nan, 0, 1]),
            (['30m', '60m'], 'hours', [0.5, 1.0]),
        ]
        if '0.16' >= pd.__version__:
            # not quite sure why, but these examples don't work on older pandas
            examples.extend([(np.timedelta64('NaT', 'ns'), 'days', np.nan),
                             (['NaT', 'NaT'], 'days', [np.nan, np.nan])])

        for timedeltas, units, numbers in examples:
            timedeltas = pd.to_timedelta(timedeltas, box=False)
            numbers = np.array(numbers)

            expected = numbers
            actual, _ = conventions.encode_cf_timedelta(timedeltas, units)
            self.assertArrayEqual(expected, actual)
            self.assertEqual(expected.dtype, actual.dtype)

            if units is not None:
                expected = timedeltas
                actual = conventions.decode_cf_timedelta(numbers, units)
                self.assertArrayEqual(expected, actual)
                self.assertEqual(expected.dtype, actual.dtype)

        expected = np.timedelta64('NaT', 'ns')
        actual = conventions.decode_cf_timedelta(np.array(np.nan), 'days')
        self.assertArrayEqual(expected, actual)
dataset/ETHPy150Open pydata/xarray/xarray/test/test_conventions.py/TestDatetime.test_cf_timedelta/swapped operands of `>=`