code: func (s *ActivityService) ListStarred(ctx context.Context, user string, opt *ActivityListStarredOptions) ([]*StarredRepository, *Response, error) {
  	var u string
  	if user != "" {
  		u = fmt.Sprintf("users/%v/starred", user)
  	} else {
  		u = "user/starred"
  	}
  	u, err := addOptions(u, opt)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	// TODO: remove custom Accept header when APIs fully launch
  	acceptHeaders := []string{mediaTypeStarringPreview, mediaTypeTopicsPreview}
  	req.Header.Set("Accept", strings.Join(acceptHeaders, ", "))
  
  	var repos []*StarredRepository
  	resp, err := s.client.Do(ctx, req, &repos)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return repos, resp, nil
  }
docs: // ListStarred lists all the repos starred by a user. Passing the empty string
  // will list the starred repositories for the authenticated user.
  //
  // GitHub API docs: https://developer.github.com/v3/activity/starring/#list-repositories-being-starred