fetch_or_cache_partial

# File actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb, line 45
      def fetch_or_cache_partial(cached_partials, order_by))
        order_by.map do |cache_key|
          cached_partials.fetch(cache_key) do
            yield.tap do |rendered_partial|
              collection_cache.write(cache_key, rendered_partial)
            end
          end
        end