<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def search_phenotype_association_sets(self, dataset_id):
 """ Returns an iterator over the PhenotypeAssociationSets on the server. """

        request = protocol.SearchPhenotypeAssociationSetsRequest()
        request.dataset_id = dataset_id
        request.page_size = pb.int(self._page_size)
        return self._run_search_request(
            request, "phenotypeassociationsets",
            protocol.SearchPhenotypeAssociationSetsResponse)