code: func (c *CookieOverseer) Set(w http.ResponseWriter, r *http.Request, value string) error {
  	ev, err := c.encode(value)
  	if err != nil {
  		return errors.Wrap(err, "unable to encode session value into cookie")
  	}
  
  	w.(cookieWriter).SetCookie(c.options.makeCookie(ev))
  
  	return nil
  }
docs: // Set a value into the cookie overseer