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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def bed(args):
 """ %prog bed btabfile Convert btab to bed format. """

    from jcvi.formats.blast import BlastLine
    p = OptionParser(bed.__doc__)

    opts, args = p.parse_args(args)

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

    btabfile, = args
    btab = Btab(btabfile)
    for b in btab:
        Bline = BlastLine(b.blastline)
        print(Bline.bedline)