@Override
  protected void releaseNodeIterator(Iterator<N> nodeIterator) {
    if (nodeIterator instanceof IMNodeIterator) {
      ((IMNodeIterator<N>) nodeIterator).close();
    }
  }
The interface to start the traversal. The node process should be defined before traversal by
overriding or implement concerned methods.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/traverser/Traverser.java