code: func (s *ProjectsService) GetProjectCard(ctx context.Context, columnID int64) (*ProjectCard, *Response, error) {
  	u := fmt.Sprintf("projects/columns/cards/%v", columnID)
  	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", mediaTypeProjectsPreview)
  
  	card := &ProjectCard{}
  	resp, err := s.client.Do(ctx, req, card)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return card, resp, nil
  }
docs: // GetProjectCard gets a card in a column of a GitHub Project.
  //
  // GitHub API docs: https://developer.github.com/v3/projects/cards/#get-a-project-card