code: public int getLastChild(int nodeHandle)
    {
  
      int identity = makeNodeIdentity(nodeHandle);
      int child = _firstch(identity);
      int lastChild = DTM.NULL;
  
      while (child != DTM.NULL)
      {
        lastChild = child;
        child = _nextsib(child);
      }
  
      return makeNodeHandle(lastChild);
    }
docs: Given a node handle, advance to its last child.
  If not yet resolved, waits for more nodes to be added to the document and
  tries again.
  
  @param nodeHandle int Handle of the node.
  @return int Node-number of last child,
  or DTM.NULL to indicate none exists.