def METHOD_NAME(multiindex_dataframe):
    """Tests clean_names default args on a multi-index dataframe."""
    df = multiindex_dataframe.clean_names()
    levels = [
        ["a", "bell_chart", "decorated_elephant"],
        ["b", "normal_distribution", "r_i_p_rhino"],
    ]
    codes = [[0, 1, 2], [0, 1, 2]]
    expected_columns = pd.MultiIndex(levels=levels, codes=codes)
    assert set(df.columns) == set(expected_columns)