code: def phenotypeAssociationSetsGenerator(self, request):
          
          dataset = self.getDataRepository().getDataset(request.dataset_id)
          return self._topLevelObjectGenerator(
              request, dataset.getNumPhenotypeAssociationSets(),
              dataset.getPhenotypeAssociationSetByIndex)
docs: Returns a generator over the (phenotypeAssociationSet, nextPageToken)
          pairs defined by the specified request