// イテレーターには次の要素が格納される
 public void Delete(ref SimpleListIterator <T> iterator)
 {
     //
     if (Count <= 1)
     {
         if (Count == 1)
         {
             sectorStack.Add(iterator.Obj);
         }
         iterator.Obj = forward = back = null; Count = 0; return;
     }
     if (iterator.Obj.next == null)
     {
         back = iterator.Obj.before;
     }
     if (iterator.Obj.before == null)
     {
         forward = iterator.Obj.next;
     }
     sectorStack.Add(iterator.Delete_ReplaceNext());
     --Count;
 }
 public void SetForward(ref SimpleListIterator <T> write)
 {
     write.Obj = forward;
 }