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: stack_exchange_onebox.rb
    path of file: ./repos/discourse/lib/onebox/engine
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Onebox
  module Engine
    class StackExchangeOnebox
      include Engine
   
    
      def self.domains
        %w[
          stackexchange.com
          stackoverflow.com
          superuser.com
          serverfault.com
          askubuntu.com
          stackapps.com
          mathoverflow.net
        ].map { |domain| Regexp.escape(domain) }
      end