code: func (l *AuditLog) createOrGetDownload(path string) (context.Context, context.CancelFunc) {
  	l.Lock()
  	defer l.Unlock()
  	ctx, ok := l.activeDownloads[path]
  	if ok {
  		return ctx, nil
  	}
  	ctx, cancel := context.WithCancel(context.TODO())
  	l.activeDownloads[path] = ctx
  	return ctx, func() {
  		cancel()
  		l.Lock()
  		defer l.Unlock()
  		delete(l.activeDownloads, path)
  	}
  }
docs: // createOrGetDownload creates a new download sync entry for a given session,
  // if there is no active download in progress, or returns an existing one.
  // if the new context has been created, cancel function is returned as a
  // second argument. Caller should call this function to signal that download has been
  // completed or failed.