You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: attachment_renderer.rb
    path of file: ./repos/openproject/lib/api/helpers
    
    the code of the file until where you have to start completion: #-- copyright
# OpenProject is an open source project management software.
# Copyright (C) 2012-2024 the OpenProject GmbH
#
# 
    
      def self.content_endpoint(&)
        ->(*) {
          helpers ::API::Helpers::AttachmentRenderer

          finally do
            set_cache_headers
          end

          get do
            attachment = instance_exec(&)
            respond_with_attachment attachment, cache_seconds: fog_cache_seconds
          end
        }
      end