// this is a class library in a DLL that does a fancy conversion process to a string

namespace SecretStuff
{
    public class Converter
    {
        public string Convert(string source)
        {
            return "Result of secret algorithm: " + SecretAlgotithm(source);
        }

        private string SecretAlgotithm(string input)
        {
            return input.ToUpper();
        }
    }
}

// this is a console program that refers to the DLL above
using System;
using SecretStuff;

namespace Encapsulation
{
    class Program
    {
        static void Main(string[] args)
        {
            var converter = new Converter();
            var message = "this is a secret message.";

            Console.WriteLine(converter.Convert(message));
            Console.ReadKey();
        }
    }
}