/// <summary>
        /// Entry point into console application.
        /// </summary>
        public void Execute()
        {
            // Create chatroom
            Chatroom chatroom = new Chatroom();

            // Create participants and register them
            Participant George = new Beatle("George");
            Participant Paul   = new Beatle("Paul");
            Participant Ringo  = new Beatle("Ringo");
            Participant John   = new Beatle("John");
            Participant Yoko   = new NonBeatle("Yoko");

            chatroom.Register(George);
            chatroom.Register(Paul);
            chatroom.Register(Ringo);
            chatroom.Register(John);
            chatroom.Register(Yoko);

            // Chatting participants
            Yoko.Send("John", "Hi John!");
            Paul.Send("Ringo", "All you need is love");
            Ringo.Send("George", "My sweet Lord");
            Paul.Send("John", "Can't buy me love");
            John.Send("Yoko", "My sweet love");
        }
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        private static void Main()
        {
            // Create chatroom
              Chatroom chatroom = new Chatroom();

              // Create participants and register them
              Participant George = new Beatle("George");
              Participant Paul = new Beatle("Paul");
              Participant Ringo = new Beatle("Ringo");
              Participant John = new Beatle("John");
              Participant Yoko = new NonBeatle("Yoko");

              chatroom.Register(George);
              chatroom.Register(Paul);
              chatroom.Register(Ringo);
              chatroom.Register(John);
              chatroom.Register(Yoko);

              // Chatting participants
              Yoko.Send("John", "Hi John!");
              Paul.Send("Ringo", "All you need is love");
              Ringo.Send("George", "My sweet Lord");
              Paul.Send("John", "Can't buy me love");
              John.Send("Yoko", "My sweet love");

              // Wait for user
              Console.ReadKey();
        }