def METHOD_NAME(
    admin_client, edit_link, theme, default_theme
):
    theme.parent = default_theme
    theme.save()
    admin_client.post(edit_link, {"name": theme.name})
    default_theme.refresh_from_db()
    theme.refresh_from_db()
    assert theme.parent is None
    assert theme.tree_id != default_theme.tree_id
    assert theme.lft == 1
    assert theme.rght == 2
    assert default_theme.lft == 1
    assert default_theme.rght == 2