code: func (b *FilterQueryBuilder) AddQueryStringFilter(querystring string, analyseWildcard bool) *FilterQueryBuilder {
  	if len(strings.TrimSpace(querystring)) == 0 {
  		return b
  	}
  
  	b.filters = append(b.filters, &QueryStringFilter{
  		Query:           querystring,
  		AnalyzeWildcard: analyseWildcard,
  	})
  	return b
  }
docs: // AddQueryStringFilter adds a new query string filter