code: func (s *ScrollService) FilterPath(filterPath ...string) *ScrollService {
  	s.filterPath = append(s.filterPath, filterPath...)
  	return s
  }
docs: // FilterPath allows reducing the response, a mechanism known as
  // response filtering and described here:
  // https://www.elastic.co/guide/en/elasticsearch/reference/7.0/common-options.html#common-options-response-filtering.