code: def seqids(args):
      
      p = OptionParser(seqids.__doc__)
      p.add_option("--maxn", default=100, type="int",
                   help="Maximum number of seqids")
      p.add_option("--prefix", help="Seqids must start with")
      p.add_option("--exclude", default="random", help="Seqids should not contain")
      opts, args = p.parse_args(args)
  
      if len(args) < 1:
          sys.exit(not p.print_help())
  
      bedfile, = args
      pf = opts.prefix
      exclude = opts.exclude
      bed = Bed(bedfile)
      s = bed.seqids
      if pf:
          s = [x for x in s if x.startswith(pf)]
      if exclude:
          s = [x for x in s if not exclude in x]
      s = s[:opts.maxn]
      print(",".join(s))
docs: %prog seqids bedfile
  
      Print out all seqids on one line. Useful for graphics.karyotype.