'Retrieve the default subnetpool for the given IP version.'

@db_api.retry_if_session_inactive()
def get_default_subnetpool(self, context, ip_version):

    filters = {'is_default': True, 'ip_version': ip_version}
    subnetpool = self.get_subnetpools(context, filters=filters)
    if subnetpool:
        return subnetpool[0]
