code: func AttachLocation(
  	getter ResourceGetter,
  	connInfo client.ConnectionInfoGetter,
  	ctx context.Context,
  	name string,
  	opts *api.PodAttachOptions,
  ) (*url.URL, http.RoundTripper, error) {
  	return streamLocation(getter, connInfo, ctx, name, opts, opts.Container, "attach")
  }
docs: // AttachLocation returns the attach URL for a pod container. If opts.Container is blank
  // and only one container is present in the pod, that container is used.