def METHOD_NAME(data_cell_widths_N16):
    # checks that cell widths are properly upcast to float64 (this errors
    # if that is not the case).
    data, cell_widths = data_cell_widths_N16
    cell_widths = [cw.astype(np.float32) for cw in cell_widths]
    ds = load_uniform_grid(
        data,
        data["density"].shape,
        bbox=np.array([[0.0, 1.0], [0.0, 1.0], [0.0, 1.0]]),
        cell_widths=cell_widths,
    )
    _ = ds.slice(0, ds.domain_center[0])[("stream", "density")]