code: func enableVersions(externalVersions []unversioned.GroupVersion) error {
  	addVersionsToScheme(externalVersions...)
  	preferredExternalVersion := externalVersions[0]
  
  	groupMeta := latest.GroupMeta{
  		GroupVersion:  preferredExternalVersion,
  		GroupVersions: externalVersions,
  		Codec:         runtime.CodecFor(api.Scheme, preferredExternalVersion),
  		RESTMapper:    newRESTMapper(externalVersions),
  		SelfLinker:    runtime.SelfLinker(accessor),
  		InterfacesFor: interfacesFor,
  	}
  
  	if err := latest.RegisterGroup(groupMeta); err != nil {
  		return err
  	}
  	api.RegisterRESTMapper(groupMeta.RESTMapper)
  	return nil
  }
docs: // TODO: enableVersions should be centralized rather than spread in each API
  // group.