def merge(args):
    """
    %prog merge bedfiles > newbedfile

    Concatenate bed files together. Performing seqid and name changes to avoid
    conflicts in the new bed file.
    """
    p = OptionParser(merge.__doc__)
    p.set_outfile()
    opts, args = p.parse_args(args)

    if len(args) < 1:
        sys.exit(not p.print_help())

    bedfiles = args
    fw = must_open(opts.outfile, "w")
    for bedfile in bedfiles:
        bed = Bed(bedfile)
        pf = op.basename(bedfile).split(".")[0]
        for b in bed:
            b.seqid = "_".join((pf, b.seqid))
            print(b, file=fw)
%prog merge bedfiles > newbedfile

    Concatenate bed files together. Performing seqid and name changes to avoid
    conflicts in the new bed file.