code: func (c *SDKConfig) Client(ctx context.Context) *http.Client {
  	return &http.Client{
  		Transport: &oauth2.Transport{
  			Source: c.TokenSource(ctx),
  		},
  	}
  }
docs: // Client returns an HTTP client using Google Cloud SDK credentials to
  // authorize requests. The token will auto-refresh as necessary. The
  // underlying http.RoundTripper will be obtained using the provided
  // context. The returned client and its Transport should not be
  // modified.