code: func CloneRCS(ctx context.Context, id RCSBackend, repo, path string) (RCS, error) {
  	if be, found := rcsRegistry[id]; found {
  		out.Debug(ctx, "Cloning with %s", be.String())
  		return be.Clone(ctx, repo, path)
  	}
  	return nil, errors.Wrapf(ErrNotFound, "unknown backend: %d", id)
  }
docs: // CloneRCS clones an existing repository from a remote.