def new_page(record, values = [])
      idx = @page_counter
      @page_counter += 1
      mark_page_as_modified(IDListPage.new(self, record, idx, values))
      idx
    end
def new_page(record, values = [])
      idx = @page_counter
      @page_counter += 1
      mark_page_as_modified(IDListPage.new(self, record, idx, values))
      idx
    end
Create a new IDListPage and register it.
 @param record [IDListPageRecord] The corresponding record.
 @param values [Array of Integer] The values stored in the page
 @return [IDListPage]