code: func (s ReactionsService) CreatePullRequestCommentReaction(ctx context.Context, owner, repo string, id int64, content string) (*Reaction, *Response, error) {
  	u := fmt.Sprintf("repos/%v/%v/pulls/comments/%v/reactions", owner, repo, id)
  
  	body := &Reaction{Content: String(content)}
  	req, err := s.client.NewRequest("POST", u, body)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	// TODO: remove custom Accept headers when APIs fully launch.
  	req.Header.Set("Accept", mediaTypeReactionsPreview)
  
  	m := &Reaction{}
  	resp, err := s.client.Do(ctx, req, m)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return m, resp, nil
  }
docs: // CreatePullRequestCommentReaction creates a reaction for a pull request review comment.
  // Note that if you have already created a reaction of type content, the
  // previously created reaction will be returned with Status: 200 OK.
  // The content should have one of the following values: "+1", "-1", "laugh", "confused", "heart", "hooray".
  //
  // GitHub API docs: https://developer.github.com/v3/reactions/#create-reaction-for-an-issue-comment