//Define the Memento Object.

//Define the Memento class (object) which is responsible for implementing the functionality to save and restore application state.
//The application data is saved (serialized) into a binary format.
[Serializable]
public class Memento
{
private MemoryStream _stream = new MemoryStream();
private BinaryFormatter _formatter = new BinaryFormatter();

public object Restore()
{
_stream.Seek(0, SeekOrigin.Begin);
object o = _formatter.Deserialize(_stream);
_stream.Close();

return (o);
}

public Memento Save(object o)
{
_formatter.Serialize(_stream, o);

return this;
}
}