public Memo Pop()
{
if (_top is null)
{
return(null);
}
var val = _top.Value;
_top = _top.NextItem;
return(val);
}
public void Push(Memo memo)
{
var item = new MemoStackItem(_top, memo);
_top = item;
}
public MemoStackItem(MemoStackItem nextItem, Memo value)
{
NextItem = nextItem;
Value = value;
}
