'Disassociate a floating IP from the instance.'

@base_api.refresh_cache
def disassociate_floating_ip(self, context, instance, address, affect_auto_assigned=False):

    client = get_client(context)
    fip = self._get_floating_ip_by_address(client, address)
    client.update_floatingip(fip['id'], {'floatingip': {'port_id': None}})
