def fetch_and_parse_pmid_list(list, extraction_fields = nil)
      @hercules_articles.fight(list) do |pmid|
        process_detail_page(pmid, extraction_fields) do |article|
          yield article if block_given?
        end
      end
    end
def fetch_and_parse_pmid_list(list, extraction_fields = nil)
      @hercules_articles.fight(list) do |pmid|
        process_detail_page(pmid, extraction_fields) do |article|
          yield article if block_given?
        end
      end
    end
not test covered