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: user_notification_renderer.rb
    path of file: ./repos/discourse/app/services
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

class UserNotificationRenderer < ActionView::Base
  include ApplicationHelper
  include UserNotificationsHelper
  include EmailHelper

  LOCK = Mutex.new

  def sel
    
  def self.render(*args)
    LOCK.synchronize do
      @instance ||=
        UserNotificationRenderer.with_empty_template_cache.with_view_paths(
          Rails.configuration.paths["app/views"],
        )
      @instance.render(*args)
    end
  end