static void Main(string[] args)
        {
            Executavel executavel = new Executavel();
            OperacaoA  operacaoA  = new OperacaoA();

            executavel.ExecutarOperacao(operacaoA);

            OperacaoB operacaoB = new OperacaoB();

            //executavel.ExecutarOperacao(operacaoB);

            Console.ReadKey();
        }
 public void ExecutarOperacao(OperacaoA operacao)
 {
     operacaoA = operacao;
     operacaoA.Executar();
 }