code: func (s Storage) getModuleRoot(dir string) (string, error) {
  	manifest, err := s.loadManifest()
  	if err != nil {
  		return "", err
  	}
  
  	for _, mod := range manifest.Modules {
  		if mod.Dir == dir {
  			return mod.Root, nil
  		}
  	}
  	return "", nil
  }
docs: // return only the root directory of the module stored in dir.