code: func (s *GistsService) ListForks(ctx context.Context, id string) ([]*GistFork, *Response, error) {
  	u := fmt.Sprintf("gists/%v/forks", id)
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	var gistForks []*GistFork
  	resp, err := s.client.Do(ctx, req, &gistForks)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return gistForks, resp, nil
  }
docs: // ListForks lists forks of a gist.
  //
  // GitHub API docs: https://developer.github.com/v3/gists/#list-gist-forks