code: func (fsh *Handler) GetFileNames(paths []string) (files []string, err error) {
  	for _, path := range paths {
  		err := filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
  			if err != nil {
  				return err
  			}
  			if info == nil || info.IsDir() {
  				return nil
  			}
  			files = append(files, path)
  			return nil
  		})
  		if err != nil {
  			err = errors.Errorf("failed to traverse through %s: %v", path, err)
  		}
  	}
  	return files, err
  }
docs: // GetFileNames is an implementation of the file system API interface