def METHOD_NAME(self):
    # same length
    self.assertEqual(distance_metric(self.list_a, self.list_b), 4.4)
    # different length
    self.assertEqual(distance_metric(self.list_b, self.list_c), 1.0)
    # sanity check, same objects
    self.assertEqual(distance_metric(self.list_b, self.list_b), 0.0)