docs: func (s CookieSigner) Sign(u string, expires time.Time, opts ...func(*CookieOptions)) ([]*http.Cookie, error) {
  	scheme, err := cookieURLScheme(u)
  	if err != nil {
  		return nil, err
  	}
  
  	resource, err := CreateResource(scheme, u)
  	if err != nil {
  		return nil, err
  	}
  
  	p := NewCannedPolicy(resource, expires)
  	return createCookies(p, s.keyID, s.privKey, s.Opts.apply(opts...))
  }