code: func (s *GistsService) IsStarred(ctx context.Context, id string) (bool, *Response, error) {
  	u := fmt.Sprintf("gists/%v/star", id)
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return false, nil, err
  	}
  	resp, err := s.client.Do(ctx, req, nil)
  	starred, err := parseBoolResponse(err)
  	return starred, resp, err
  }
docs: // IsStarred checks if a gist is starred by authenticated user.
  //
  // GitHub API docs: https://developer.github.com/v3/gists/#check-if-a-gist-is-starred