def METHOD_NAME(cls, parameter_set="default"):
    """Return testing parameter settings for the estimator."""
    params1 = {"mu": [[0, 1], [2, 3], [4, 5]], "sigma": 1}
    params2 = {
        "mu": 0,
        "sigma": 1,
        "index": pd.Index([1, 2, 5]),
        "columns": pd.Index(["a", "b"]),
    }
    return [params1, params2]