Returns an iterator over the Variants fulfilling the specified
        conditions from the specified VariantSet.

        :param str variant_set_id: The ID of the
            :class:`ga4gh.protocol.VariantSet` of interest.
        :param int start: Required. The beginning of the window (0-based,
            inclusive) for which overlapping variants should be returned.
            Genomic positions are non-negative integers less than reference
            length. Requests spanning the join of circular genomes are
            represented as two requests one on each side of the join
            (position 0).
        :param int end: Required. The end of the window (0-based, exclusive)
            for which overlapping variants should be returned.
        :param str reference_name: The name of the
            :class:`ga4gh.protocol.Reference` we wish to return variants from.
        :param list call_set_ids: Only return variant calls which belong to
            call sets with these IDs. If an empty array, returns variants
            without any call objects. If null, returns all variant calls.

        :return: An iterator over the :class:`ga4gh.protocol.Variant` objects
            defined by the query parameters.
        :rtype: iter

def search_variants(
            self, variant_set_id, start=None, end=None, reference_name=None,
            call_set_ids=None):
        """
        Returns an iterator over the Variants fulfilling the specified
        conditions from the specified VariantSet.

        :param str variant_set_id: The ID of the
            :class:`ga4gh.protocol.VariantSet` of interest.
        :param int start: Required. The beginning of the window (0-based,
            inclusive) for which overlapping variants should be returned.
            Genomic positions are non-negative integers less than reference
            length. Requests spanning the join of circular genomes are
            represented as two requests one on each side of the join
            (position 0).
        :param int end: Required. The end of the window (0-based, exclusive)
            for which overlapping variants should be returned.
        :param str reference_name: The name of the
            :class:`ga4gh.protocol.Reference` we wish to return variants from.
        :param list call_set_ids: Only return variant calls which belong to
            call sets with these IDs. If an empty array, returns variants
            without any call objects. If null, returns all variant calls.

        :return: An iterator over the :class:`ga4gh.protocol.Variant` objects
            defined by the query parameters.
        :rtype: iter
        """
        request = protocol.SearchVariantsRequest()
        request.reference_name = pb.string(reference_name)
        request.start = pb.int(start)
        request.end = pb.int(end)
        request.variant_set_id = variant_set_id
        request.call_set_ids.extend(pb.string(call_set_ids))
        request.page_size = pb.int(self._page_size)
        return self._run_search_request(
            request, "variants", protocol.SearchVariantsResponse)