docs: def main(reactor):
      """Main command line entry point."""
      parser = argparse.ArgumentParser(
          description='Fetch a URI or series of URIs and print a title '
                      'or summary for each.',
          epilog='If no URIs are passed on the command line, they are '
                 'read from standard input, one per line.')
      parser.add_argument(
          'uris', metavar='URI', nargs='*', help='URI to fetch')
      parser.add_argument(
          '-H', '--hostname-tag', action='store_true',
          help='prefix titles with a hostname tag')
      args = parser.parse_args()
      uris = args.uris or imap(lambda x: x.strip(), sys.stdin)
      finished = DeferredList([
          fetch_title(uri.decode(locale.getpreferredencoding()),
                      hostname_tag=args.hostname_tag, friendly_errors=True)
          for uri in uris])
      finished.addCallback(print_and_exit)
      return finished