def tagged_to_different_mainstream_browse_pages
      all_content_ids = (tagged_to_same_mainstream_browse_page + parents_tagged_to_same_mainstream_browse_page).map(&:content_id)

      @tagged_to_different_mainstream_browse_pages ||= content_item.related_links.reject do |related_item|
        all_content_ids.include?(related_item.content_id)
      end
    end
def tagged_to_different_mainstream_browse_pages
      all_content_ids = (tagged_to_same_mainstream_browse_page + parents_tagged_to_same_mainstream_browse_page).map(&:content_id)

      @tagged_to_different_mainstream_browse_pages ||= content_item.related_links.reject do |related_item|
        all_content_ids.include?(related_item.content_id)
      end
    end
This will return related links that are tagged to mainstream browse
 pages unrelated to the main content item.