$cookie_jar->add_cookie_header($request);
      The add_cookie_header() method will set the appropriate
      Cookie:-header for the *HTTP::Request* object given as argument. The
      $request must have a valid url attribute before this method is
      called.

  $cookie_jar->extract_cookies($response);
      The extract_cookies() method will look for Set-Cookie: and
      Set-Cookie2: headers in the *HTTP::Response* object passed as
      argument. Any of these headers that are found are used to update the
      state of the $cookie_jar.