def check_output_filepath(filepath):
    """
    Check and return an appropriate output_filepath parameter.

    Ensures the file is a csv file.  Ensures a value is set.  If
    a value is not set or is not a csv, it will return a
    default value.

    :param filepath:  string filepath name

    :returns: a string representing a filepath location.
    """
    if filepath.endswith('.csv'):
        return filepath

    return "clean_rules_report.csv"