code: func (b *URLBackoff) baseUrlKey(rawurl *url.URL) string {
  	// Simple implementation for now, just the host.
  	// We may backoff specific paths (i.e. "pods") differentially
  	// in the future.
  	host, err := url.Parse(rawurl.String())
  	if err != nil {
  		klog.V(4).Infof("Error extracting url: %v", rawurl)
  		panic("bad url!")
  	}
  	return host.Host
  }
docs: // baseUrlKey returns the key which urls will be mapped to.
  // For example, 127.0.0.1:8080/api/v2/abcde -> 127.0.0.1:8080.