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: extension_denylist.rb
    path of file: ./repos/carrierwave/lib/carrierwave/uploader
    
    the code of the file until where you have to start completion: module CarrierWave
  module Uploader
    module ExtensionDenylist
      extend ActiveSupport::Concern

      included do
        before :cache, :check_extension_deny
    
      def check_extension_denylist!(new_file)
        denylist = extension_denylist
        if !denylist && respond_to?(:extension_blacklist) && extension_blacklist
          ActiveSupport::Deprecation.warn "#extension_blacklist is deprecated, use #extension_denylist instead." unless instance_variable_defined?(:@extension_blacklist_warned)
          @extension_blacklist_warned = true
          denylist = extension_blacklist
        end