docs: private boolean containsElmentWithId(Node node, String id) {
          String nodeName = node.getNodeName();
          if ("channel".equals(nodeName) || "folder".equals(nodeName)) {
              Element e = (Element) node;
              if (id.equals(e.getAttribute("ID"))) {
                  return true;
              }
              if ("folder".equals(nodeName)) {
                  for (Node child = e.getFirstChild();
                          child != null;
                          child = child.getNextSibling()) {
                      if (containsElmentWithId(child, id)) {
                          return true;
                      }
                  }
              }
          }
          return false;
      }