static Set<S> ai_ignoredWebs() {    
  new Matches m;
  new Set<S> ignoredWebs;
  for (WebNode n : ai_index_search_dollarX("$X", "can be", "ignored"))
    if (swic(web_text(n), "web ", m))
      ignoredWebs.add($1);
  ret ignoredWebs;
}