public object Pop()
{
if (top == null) throw new InvalidOperationException();
object result = top.data;
top = top.next;
return result;
}
public Entry(Entry next, object data)
{
this.next = next;
this.data = data;
}
public void Push(object data)
{
top = new Entry(top, data);
}
public Entry(Entry next, object data)
{
next_ = next;
data_ = data;
}