code: def _filterSearchFeaturesRequest(self, reference_name, gene_symbol, name,
                                       start, end):
          
          filters = []
          query = self._baseQuery()
          filters = []
          location = self._findLocation(reference_name, start, end)
          if location:
              filters.append("?feature = <{}>".format(location))
          if gene_symbol:
              filters.append('regex(?feature_label, "{}")')
          if name:
              filters.append(
                  'regex(?feature_label, "{}")'.format(name))
          # apply filters
          filter = "FILTER ({})".format(' && '.join(filters))
          if len(filters) == 0:
              filter = ""
          query = query.replace("#%FILTER%", filter)
          return query
docs: formulate a sparql query string based on parameters