code: def _validate_danglers(self):
          
          for query, warning in zip(DANGLER_QUERIES, DANGLER_WARNINGS):
              dangler_count = self.gtfs.execute_custom_query(query).fetchone()[0]
              if dangler_count > 0:
                  if self.verbose:
                      print(str(dangler_count) + " " + warning)
                  self.warnings_container.add_warning(warning, self.location, count=dangler_count)
docs: Checks for rows that are not referenced in the the tables that should be linked
  
          stops <> stop_times using stop_I
          stop_times <> trips <> days, using trip_I
          trips <> routes, using route_I
          :return: