Try to download on-demand class.

    @return: Tuple of (bool, bool), where the first bool indicates whether
        errors occurred while parsing syllabus, the second bool indicates
        whether the course appears to be completed.
    @rtype: (bool, bool)

def download_class(session, args, class_name):
    """
    Try to download on-demand class.

    @return: Tuple of (bool, bool), where the first bool indicates whether
        errors occurred while parsing syllabus, the second bool indicates
        whether the course appears to be completed.
    @rtype: (bool, bool)
    """
    logging.debug('Downloading new style (on demand) class %s', class_name)
    return download_on_demand_class(session, args, class_name)