static void Main(string[] args)
{
OldClass obj = new OldClass();
obj.Test1();
obj.Test2();
//Calling exrension methods
obj.Text3();
obj.Text4(10);
obj.Text5();
Console.ReadLine();
}
public static void Text3(this OldClass O)
{
Console.WriteLine("Method Three");
}
public static void Text5(this OldClass O)
{
Console.WriteLine("Method Five:" + O.x);
}
public static void Text4(this OldClass O, int x)
{
Console.WriteLine("Method Four: " + x);
}