class ActionView::CollectionRenderer

def render_collection(collection, view, path, template, layout, block)
  identifier = (template && template.identifier) || path
  ActiveSupport::Notifications.instrument(
    "render_collection.action_view",
    identifier: identifier,
    layout: layout && layout.virtual_path,
    count: collection.length
  ) do |payload|
    spacer = if @options.key?(:spacer_template)
      spacer_template = find_template(@options[:spacer_template], @locals.keys)
      build_rendered_template(spacer_template.render(view, @locals), spacer_template)
    else
      RenderedTemplate::EMPTY_SPACER
    end
    collection_body = if template
      cache_collection_render(payload, view, template, collection) do |filtered_collection|
        collection_with_template(view, template, layout, filtered_collection)
      end
    else
      collection_with_template(view, nil, layout, collection)
    end
    return RenderedCollection.empty(@lookup_context.formats.first) if collection_body.empty?
    build_rendered_collection(collection_body, spacer)
  end
end