code: func (p *OpenPrinter) Server() *Server {
  	if p.verify == nil {
  		panic(fmt.Errorf("Server: VerifyClaim has not succeeded"))
  	}
  	srv := &Server{
  		auth: p.auth,
  	}
  	return srv
  }
docs: // Server returns a server that can manage the newly created printer.
  // This method is only a convenience: the returned server is the one
  // that would be returned by NewServer(p.Auth()).
  //
  // Server must be called only after VerifyClaim has succeeded.