docs: def webify_file(srcfilename: str, destfilename: str) -> None:
      """
      Rewrites a file from ``srcfilename`` to ``destfilename``, HTML-escaping it
      in the process.
      """
      with open(srcfilename) as infile, open(destfilename, 'w') as ofile:
          for line_ in infile:
              ofile.write(escape(line_))