render_collection

# File actionview/lib/action_view/renderer/partial_renderer.rb, line 317
    def render_collection
      return nil if @collection.blank?

      if @options.key?(:spacer_template)
        spacer = find_template(@options[:spacer_template], @locals.keys).render(@view, @locals)
      end

      result = @template ? collection_with_template : collection_without_template
      result.join(spacer).html_safe
    end