List all availability zones in the current region

def _list_availability_zones(vm_=None):
    '''
    List all availability zones in the current region
    '''
    ret = {}

    params = {'Action': 'DescribeAvailabilityZones',
              'Filter.0.Name': 'region-name',
              'Filter.0.Value.0': get_location(vm_)}
    result = aws.query(params,
                       location=get_location(vm_),
                       provider=get_provider(),
                       opts=__opts__,
                       sigver='4')

    for zone in result:
        ret[zone['zoneName']] = zone['zoneState']

    return ret