code: func StorageBackends() []string {
  	bes := make([]string, 0, len(storageNameToBackendMap))
  	for k := range storageNameToBackendMap {
  		bes = append(bes, k)
  	}
  	sort.Strings(bes)
  	return bes
  }
docs: // StorageBackends returns the list of registered storage backends.