def _get_host(self, region):
        """
        Returns correctly formatted host. Accepted formats:

            * simple region name, eg 'us-west-1' (see list in AWS_REGIONS)
            * full host name, eg 's3-us-west-1.amazonaws.com'.
        """
        if 'us-east-1' in region:
            return 's3.amazonaws.com'
        elif region in AWS_REGIONS:
            return 's3-%s.amazonaws.com' % region
        elif region and not REGION_RE.findall(region):
            raise ImproperlyConfigured('AWS_REGION improperly configured!')
        # can be full host or empty string, default region
        return  region