def test_skewness(self):
        self.assertEqualOnAllArrayTypes(skewness, [1, 1, 1, 2, 2, 2], 0)
        self.assertAlmostEqualOnAllArrayTypes(
            skewness, [1, 1, 1, 2, 2], 0.6085806194501855
        )
        self.assertEqualOnAllArrayTypes(skewness, [1, 1, 1], 0)
        self.assertIsNanOnAllArrayTypes(skewness, [1, 1])