code: func (s *GistsService) GetComment(ctx context.Context, gistID string, commentID int64) (*GistComment, *Response, error) {
  	u := fmt.Sprintf("gists/%v/comments/%v", gistID, commentID)
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	c := new(GistComment)
  	resp, err := s.client.Do(ctx, req, c)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return c, resp, nil
  }
docs: // GetComment retrieves a single comment from a gist.
  //
  // GitHub API docs: https://developer.github.com/v3/gists/comments/#get-a-single-comment