# File lib/action_controller/metal/conditional_get.rb, line 73
    def expires_in(seconds, options = {}) #:doc:
      response.cache_control.merge!(:max_age => seconds, :public => options.delete(:public))
      options.delete(:private)

      response.cache_control[:extras] = options.map {|k,v| "#{k}=#{v}"}
    end