def METHOD_NAME(self):
    # Check that the order of the load is unchanged if a land mask
    # has already been seen.
    f1, mask = self.pp_field, self.land_mask_field
    mask2 = deepcopy(mask)
    result = list(pp._interpret_fields([mask, f1, mask2]))
    self.assertEqual(result, [mask, f1, mask2])