code: func NewClient(prefix string, apiVersion string, version string,
  	token TokenHolder, t http.RoundTripper) *Client {
  
  	rt := &registryRoundTripper{
  		DefaultRequestDoer: DefaultRequestDoer{
  			Client: &http.Client{
  				Transport: t,
  				Timeout:   time.Minute,
  			},
  			Host: prefix,
  		},
  
  		apiVersion: apiVersion,
  		version:    version,
  		holder:     token,
  	}
  
  	return NewClientWithRoundTripper(rt)
  }
docs: // NewClient returns a new Client.