def METHOD_NAME():
    in_labels = deepcopy(ref_in_labels)
    out_labels = combine_labels([in_labels], [[2, 4, 6]],
                                ('out_labels_ids', [1, 2, 3]), background_id=0,
                                merge_groups=False)
    exp_labels = deepcopy(ref_out_labels)
    exp_labels[exp_labels == 2] = 1
    exp_labels[exp_labels == 4] = 2
    exp_labels[exp_labels == 6] = 3
    assert_equal(out_labels, exp_labels)