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: deepl.rb
    path of file: ./repos/mastodon/app/lib/translation_service
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

class TranslationService::DeepL < Translat
    
  def languages
    source_languages = [nil] + fetch_languages('source')

    # In DeepL, EN and PT are deprecated in favor of EN-GB/EN-US and PT-BR/PT-PT, so
    # they are supported but not returned by the API.
    target_languages = %w(en pt) + fetch_languages('target')

    source_languages.index_with { |language| target_languages.without(nil, language) }
  end