# File lib/typhoeus/response/informations.rb, line 47
      def response_headers
        return options[:response_headers] if options[:response_headers]
        if mock? && h = options[:headers]
            h.map{ |k,v| [k, v.respond_to?(:join) ? v.join : v] }.
              map{ |e| "#{e.first}: #{e.last}" }.
              join("\r\n")
        end
      end