Наследование: StreamWriter, IDisposable
 static void WriteOnFLushableLazy()
 {
     Console.WriteLine("Write and forget to flush and dispose...");
     StreamWriter fs = new StreamFlushable("out.txt");
     fs.Write("Ola ");
     fs.WriteLine("Mundo");
     fs.WriteLine("Adeus 123");
 }
 static void WriteOnFLushable()
 {
     Console.WriteLine("Write and forget to flush and dispose...");
     StreamWriter fs = new StreamFlushable(new FileStream("out.txt", FileMode.Create));
     fs.Write("Ola ");
     fs.WriteLine("Mundo");
     fs.WriteLine("Adeus 123");
 }