def test_modify_uns_in_copy():
    # https://github.com/theislab/anndata/issues/571
    adata = ad.AnnData(np.ones((5, 5)), uns={"parent": {"key": "value"}})
    adata_copy = adata[:3].copy()
    adata_copy.uns["parent"]["key"] = "new_value"
    assert adata.uns["parent"]["key"] != adata_copy.uns["parent"]["key"]
def union(matches, root, cwd):
    """Union a list of matchers.

    If the list is empty, return nevermatcher.
    If the list only contains one non-None value, return that matcher.
    Otherwise return a union matcher.
    """
    matches = list(filter(None, matches))
    if len(matches) == 0:
        return nevermatcher(root, cwd)
    elif len(matches) == 1:
        return matches[0]
    else:
        return unionmatcher(matches)