static S ai_dropDroppablePrefix(S s) {
  for (WebNode node : ai_search_dollarX_verified("$X", "is", "a droppable prefix")) {
    if (isQuoted(web_text(node))) {
      S tail = web_unquote(node);
      if (nempty(tail) && swic(s, tail)) {
        print("Dropping prefix: " + quote(tail));
        ret trim(substring(s, l(tail)));
      }
    }
  }
  ret s;
}