static S hrefresh(S target) {
  ret hrefresh(0, target);
}

static S hrefresh(double seconds) {
  ret hrefresh(seconds, "");
}

static S hrefresh(double seconds, S target) {
  ret tag("meta", "", "http-equiv", "refresh", "content", iceil(seconds) + (nempty(target) ? "; url=" + target : ""));
}