code: func NewStreamExecutor(upgrader httpstream.UpgradeRoundTripper, fn func(http.RoundTripper) http.RoundTripper, method string, url *url.URL) (StreamExecutor, error) {
  	var rt http.RoundTripper = upgrader
  	if fn != nil {
  		rt = fn(rt)
  	}
  	return &streamExecutor{
  		upgrader:  upgrader,
  		transport: rt,
  		method:    method,
  		url:       url,
  	}, nil
  }
docs: // NewStreamExecutor upgrades the request so that it supports multiplexed bidirectional
  // streams. This method takes a stream upgrader and an optional function that is invoked
  // to wrap the round tripper. This method may be used by clients that are lower level than
  // Kubernetes clients or need to provide their own upgrade round tripper.