code: func (r *Request) Namespace(namespace string) *Request {
  	if r.err != nil {
  		return r
  	}
  	if r.namespaceSet {
  		r.err = fmt.Errorf("namespace already set to %q, cannot change to %q", r.namespace, namespace)
  		return r
  	}
  	if msgs := IsValidPathSegmentName(namespace); len(msgs) != 0 {
  		r.err = fmt.Errorf("invalid namespace %q: %v", namespace, msgs)
  		return r
  	}
  	r.namespaceSet = true
  	r.namespace = namespace
  	return r
  }
docs: // Namespace applies the namespace scope to a request (<resource>/[ns/<namespace>/]<name>)