static S html_linkURLs(S html) {
  L<S> tok = htmlTok(html);
  for (int i = 0; i < l(tok); i += 2)
    tok.set(i, tok.get(i).replaceAll("http://|www[.])[-A-Za-z0-9+&@#/%?=~_()|!:,.;]*[-A-Za-z0-9+&@#/%=~_()|]", "<a href="\"$1\">$1</a>"));
  ret join(tok);
}