static Collection<WebNode> ai_withoutInvalidNodes(Collection<WebNode> l) {
  if (l == null) null;
  for (WebNode n : l)
    if (ai_isInvalidWeb(n.web)) {
      Iterator<WebNode> it = iterator(l);
      WebNode node;
      new L<WebNode> x;
      while ((node = it.next()) != n)
        x.add(node);
      while (it.hasNext()) {
        node = it.next();
        if (!ai_isInvalidWeb(node.web))
          x.add(node);
      }
      ret x;
    }
  ret l;
}

static L<WebNode> ai_withoutInvalidNodes(L<WebNode> l) {
  ret (L) ai_withoutInvalidNodes((Collection) l);
}