def set_robust(robust):
    """Return generic name if user passes None to the robust parameter in a
    regression. Note: already verified that the name is valid in
    check_robust() if the user passed anything besides None to robust.

    Parameters
    ----------

    robust      : string or None
                  Object passed by the user to a regression class

    Returns
    -------

    robust      : string

    """
    if not robust:
        return 'unadjusted'
    return robust