public PageRecord ReplaceExistingPageWithNewPage(Page oldPage, int newPageid)
        {
            Page newPage = new Page(newPageid);
            Referenced = newPageid;
            PageFault = true;

            int indexInPageList = -1;
            foreach (Page page in Pages)
            {
                if (oldPage.PageNumber == page.PageNumber)
                {
                    indexInPageList = Pages.IndexOf(page);
                }
            }

            if (indexInPageList >= 0)
            {
                if (Pages.Count + 1 > maxSize)
                {
                    Pages.RemoveAt(indexInPageList);
                }                
                Pages.Insert(indexInPageList, newPage);
            }
            return (PageRecord)this;

        }
        public PageRecord CreateNewPageByPageNumberAndShiftTheOtherPages (int id)
        {
            Page newPage = new Page(id);
            Pages.Insert(0, newPage);
            Referenced = id;
            PageFault = true;

            if (Pages.Count > maxSize)
            {
                for (int i = maxSize; i <= Pages.Count; i++)
                {
                    Pages.RemoveAt(i);
                }
            }
            return (PageRecord)this;
        }