code: func (s *ReactionsService) ListPullRequestCommentReactions(ctx context.Context, owner, repo string, id int64, opt *ListOptions) ([]*Reaction, *Response, error) {
  	u := fmt.Sprintf("repos/%v/%v/pulls/comments/%v/reactions", owner, repo, id)
  	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 headers when APIs fully launch.
  	req.Header.Set("Accept", mediaTypeReactionsPreview)
  
  	var m []*Reaction
  	resp, err := s.client.Do(ctx, req, &m)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return m, resp, nil
  }
docs: // ListPullRequestCommentReactions lists the reactions for a pull request review comment.
  //
  // GitHub API docs: https://developer.github.com/v3/reactions/#list-reactions-for-an-issue-comment