Generic Reference constraint, C#

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/* while using Reference type constraints we create objects of type class, but when we pass the same object to the generic class we cannot access the methods of the cass.
off course we can have base class constraints i just have doubt on thid*/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{   public class FooBase
{
}
	public  class Foo:FooBase
	{
		
		public Foo()
		{
		}
		public Foo(Foo x,Foo y)
		{
			ThisX=x;
			ThisY=y;
		}
		
		public Foo ThisX{get;set;}
		public Foo ThisY{get;set;}
		
		public void FooMethod(Foo ob)
		{
			Console.WriteLine("Hiiiii\t"+ob); 
			
		}
		
	}
	
	public class Gen<T> where T:FooBase
	{
		
		T obj;
		
		public Gen()
		{
			
			
		}
		public Gen(T x,T y)
		{
			
			
			
			Console.WriteLine("Gen(T x,T y)\t"+x.GetType().Name.ToString()+" "+y.GetType().Name.ToString());//+" "+obj.GetType().Name.ToString());
			
		}
		
		public void Display(T ob)
		{
			obj=ob;
			Console.WriteLine("Display  "+ob.GetType().Name.ToString()+" "+obj.GetType().Name.ToString());
			obj.FooMethod(obj);
		}
		
	}
	
	public class Program
	{
		public static void Main(string[] args)
		{
			Gen<Foo> m=new Gen<Foo>();
            
			Foo ob1=new Foo();
			Foo ob2=new Foo();
			Console.WriteLine("Main "+m.GetType());
			Console.WriteLine("Main "+ob1.GetType());
			Console.WriteLine();
            
			Gen<Foo> n=new Gen<Foo>(ob1,ob2);
			Console.WriteLine();		
			m.Display(ob1);
			
			
			
		}
	}
}

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