def _annotate(args, setclus):
    """annotate transcriptional units with
    gtf/bed files provided by -b/g option"""
    logger.info("Creating bed file")
    bedfile = generate_position_bed(setclus)
    a = pybedtools.BedTool(bedfile, from_string=True)
    beds = []
    logger.info("Annotating clusters")
    if hasattr(args, 'list_files'):
        beds = args.list_files.split(",")
        for filebed in beds:
            logger.info("Using %s " % filebed)
            db = os.path.basename(filebed)
            b = pybedtools.BedTool(filebed)
            c = a.intersect(b, wo=True)
            setclus = anncluster(c, setclus, db, args.type_ann, args.feature_id)
    return setclus