    # File lib/rbot/core/utils/httputil.rb, line 291
      def initialize(bot)
        @bot = bot
        @cache = Hash.new
        @headers = {
          'Accept-Charset' => 'utf-8;q=1.0, *;q=0.8',
          'Accept-Encoding' => 'gzip;q=1, deflate;q=1, identity;q=0.8, *;q=0.2',
          'User-Agent' =>
            "rbot http util #{$version} (#{Irc::Bot::SOURCE_URL})"
        }
        debug "starting http cache cleanup timer"
        @timer = @bot.timer.add(300) {
          self.remove_stale_cache unless @bot.config['http.no_expire_cache']
        }
      end