interface is extendable

using System;
interface Printable{
   void print();
}

interface Displayable:Printable{
   void output();
}

class MyClass : Displayable{
   public void print(){
     Console.WriteLine("print");
   }
   public void output(){
     Console.WriteLine("output");
   
   }
}

class Test
{
    static void Main()
    {

        Displayable cls = new MyClass();

        cls.print();
        cls.output();

    }
}