code: func (f *FakeDockerClient) idsToNames(ids []string) ([]string, error) {
  	names := []string{}
  	for _, id := range ids {
  		names = append(names, strings.TrimPrefix(f.ContainerMap[id].Name, dockerNamePrefix))
  	}
  	return names, nil
  }
docs: // idsToNames converts container ids into names. The caller must hold the lock.