code: def children(args):
      
      p = OptionParser(children.__doc__)
      p.add_option("--parents", default="gene",
              help="list of features to extract, use comma to separate (e.g."
              "'gene,mRNA') [default: %default]")
  
      opts, args = p.parse_args(args)
  
      if len(args) != 1:
          sys.exit(not p.print_help())
  
      gff_file, = args
      g = make_index(gff_file)
      parents = set(opts.parents.split(','))
  
      for feat in get_parents(gff_file, parents):
  
          cc = [c.id for c in g.children(feat.id, 1)]
          if len(cc) <= 1:
              continue
  
          print("\t".join(str(x) for x in \
                      (feat.id, feat.start, feat.stop, "|".join(cc))))
docs: %prog children gff_file
  
      Get the children that have the same parent.