code: func (s *ScrollService) PostFilter(postFilter Query) *ScrollService {
  	s.ss = s.ss.PostFilter(postFilter)
  	return s
  }
docs: // PostFilter is executed as the last filter. It only affects the
  // search hits but not facets. See
  // https://www.elastic.co/guide/en/elasticsearch/reference/7.0/search-request-post-filter.html
  // for details.