def delete_unmarked_objects
      deleted_objects_count = 0
      each_item do |id|
        unless dynamo_is_marked?(id)
          dynamo_delete_item(id)
          deleted_objects_count += 1
          @item_counter -= 1
        end
      end
      dynamo_put_item('item_counter', @item_counter.to_s)

      deleted_objects_count
    end
def delete_unmarked_objects
      deleted_objects_count = 0
      each_item do |id|
        unless dynamo_is_marked?(id)
          dynamo_delete_item(id)
          deleted_objects_count += 1
          @item_counter -= 1
        end
      end
      dynamo_put_item('item_counter', @item_counter.to_s)

      deleted_objects_count
    end
Permanently delete all objects that have not been marked. Those are
 orphaned and are no longer referenced by any actively used object.
 @return [Integer] Count of the deleted objects.