def METHOD_NAME(
    self, regions: Sequence[Region]
) -> Mapping[str, RegionResult]:
    """
    Used to handle the requests on a given list of regions (synchronously).
    Returns a mapping of region name to response/exception.
    """
    self.ensure_control_silo()
    region_to_response_map = {}
    with ThreadPoolExecutor(max_workers=len(regions)) as executor:
        future_to_region = {
            executor.submit(self.get_response_from_region_silo, region): region
            for region in regions
        }
        for future in as_completed(future_to_region):
            region = future_to_region[future]
            try:
                region_response = future.result()
            # This will capture errors from this silo and any 4xx/5xx responses from others
            except Exception as e:
                logger.error("region_proxy_error", extra={"region": region.name, "error": e})
                region_to_response_map[region.name] = RegionResult(error=e)
            else:
                region_to_response_map[region.name] = RegionResult(response=region_response)
    if len(region_to_response_map) == 0:
        logger.error(
            "region_no_response",
            extra={"path": self.request.path, "regions": [region.name for region in regions]},
        )
        return self.response_handler(self.request)
    return region_to_response_map