code: def add_options(p, args, dist=10):
      
      p.set_beds()
      p.add_option("--dist", default=dist, type="int",
              help="Extent of flanking regions to search [default: %default]")
  
      opts, args = p.parse_args(args)
  
      if len(args) != 2:
          sys.exit(not p.print_help())
  
      blast_file, anchor_file = args
  
      return blast_file, anchor_file, opts.dist, opts
docs: scan and liftover has similar interfaces, so share common options
      returns opts, files