docs: protected IndexTreePath<E> findPathToObject(IndexTreePath<E> subtree, SpatialComparable mbr, DBIDRef id) {
      N node = getNode(subtree.getEntry());
      if(node.isLeaf()) {
        for(int i = 0; i < node.getNumEntries(); i++) {
          if(DBIDUtil.equal(((LeafEntry) node.getEntry(i)).getDBID(), id)) {
            return new IndexTreePath<>(subtree, node.getEntry(i), i);
          }
        }
      }
      // directory node
      else {
        for(int i = 0; i < node.getNumEntries(); i++) {
          if(SpatialUtil.intersects(node.getEntry(i), mbr)) {
            IndexTreePath<E> childSubtree = new IndexTreePath<>(subtree, node.getEntry(i), i);
            IndexTreePath<E> path = findPathToObject(childSubtree, mbr, id);
            if(path != null) {
              return path;
            }
          }
        }
      }
      return null;
    }