def METHOD_NAME(four_by_four_raster):
    vals = plane(four_by_four_raster, "values", "cell", normal=_NORMAL)
    truth = _plane_function(
        four_by_four_raster.xy_of_cell[:, 0],
        four_by_four_raster.xy_of_cell[:, 1],
        point=_POINT,
        normal=_NORMAL,
    )
    assert_array_equal(vals, truth)