# File lib/more/facets/class_extend.rb, line 85
  def class_extend(*mods, &block)
    @class_extension ||= Module.new do
      def self.append_features(mod)
        append_features_without_class_extension(mod)
      end
    end
    @class_extension.__send__(:include, *mods)
    @class_extension.module_eval(&block) if block_given?
    extend(@class_extension)  # extend this module too
    @class_extension
  end