Definition of C ＃ clue binary tree

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Threaded binary tree data structure
{
class Program
{
static void Main(string[] args)
{
}
}
public class ThreadNode{
public ThreadNode() { }
int data;// data elements
ThreadNode lchild, rchild;// Left and right child nodes
int ltag, rtag;// Left and right cue marks
}

}