code: func (s *GistsService) ListComments(ctx context.Context, gistID string, opt *ListOptions) ([]*GistComment, *Response, error) {
  	u := fmt.Sprintf("gists/%v/comments", gistID)
  	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
  	}
  
  	var comments []*GistComment
  	resp, err := s.client.Do(ctx, req, &comments)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return comments, resp, nil
  }
docs: // ListComments lists all comments for a gist.
  //
  // GitHub API docs: https://developer.github.com/v3/gists/comments/#list-comments-on-a-gist