static S nlToBr_withIndents(S s) {
  s = nlToBr(s);
  new StringBuilder buf;
  int i = 0;
  while (i < l(s)) {
    while (charAt(s, i) == ' ') {
      ++i;
      buf.append("&nbsp;");
    }
    int j = smartIndexOf(s, i, '\n')+1;
    buf.append(substring(s, i, j));
    i = j;
  }
  ret str(buf);
}