def readsGenerator(self, request):
        if request.referenceId is None:
            raise exceptions.UnmappedReadsNotSupported()
        if len(request.readGroupIds) < 1:
            raise exceptions.BadRequestException(
                "At least one readGroupId must be specified")
        elif len(request.readGroupIds) == 1:
            return self._readsGeneratorSingle(request)
        else:
            return self._readsGeneratorMultiple(request)
Sets an ancestor for this query.
dataset/ETHPy150Open ga4gh/server/ga4gh/backend.py/Backend.readsGenerator--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/api/datastore.py/Query.Ancestor