public virtual A Redo()
{
undos.Push(redos.Pop());
CropUndos();
undos.Peek().Do();
return(undos.Peek());
}
public virtual A Undo()
{
redos.Push(undos.Pop());
CropRedos();
redos.Peek().Undo();
return(redos.Peek());
}
public A Peek()
{
return(stack.Peek());
}
