code: def seqids(args):
      
      p = OptionParser(seqids.__doc__)
      p.add_option("--pad0", default=0, help="How many zeros to pad")
      opts, args = p.parse_args(args)
  
      if len(args) != 3:
          sys.exit(not p.print_help())
  
      prefix, start, end = args
      pad0 = opts.pad0
      start, end = int(start), int(end)
      step = 1 if start <= end else -1
  
      print(",".join(["{}{:0{}d}".format(prefix, x, pad0) \
                      for x in xrange(start, end + step, step)]))
docs: %prog seqids prefix start end
  
      Make a list of seqids for graphics.karyotype. For example:
  
      $ python -m jcvi.formats.base seqids chromosome_ 1 3
      chromosome_1,chromosome_2,chromosome_3
      $ python -m jcvi.formats.base seqids A 3 1 --pad0=2
      A03,A02,A01