@classmethod
def vm_ip(cls, vm_id):
    """Return the first usable ip address for this vm.
        Returns a (version, ip) tuple."""
    vm_info = cls.info(vm_id)
    for iface in vm_info['ifaces']:
        if iface['type'] == 'private':
            continue
        for ip in iface['ips']:
            return ip['version'], ip['ip']
