def check_correlation_method(method):
    """Confirm that the input method is currently supported.

    Parameters
    ----------
    method : str
        The correlation metric to use.

    Returns
    -------
    str
        Correctly formatted correlation method.

    """

    method = method.lower()
    avail_methods = ["pearson", "spearman", "kendall"]
    assert method in avail_methods, "method {} not supported, select one of {}".format(
        method, avail_methods
    )

    return method