<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def bed(args):
 """ %prog bed frgscffile Convert the frgscf posmap file to bed format. """

    p = OptionParser(bed.__doc__)
    opts, args = p.parse_args(args)

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

    frgscffile, = args
    bedfile = frgscffile.rsplit(".", 1)[0] + ".bed"
    fw = open(bedfile, "w")

    fp = open(frgscffile)
    for row in fp:
        f = FrgScfLine(row)
        print(f.bedline, file=fw)

    logging.debug("File written to `{0}`.".format(bedfile))

    return bedfile