How to use the zappa.asynchronous.SnsAsyncResponse function in zappa

def test_nofails_classes(self):

        boto_session = boto3.Session(region_name=os.environ['AWS_DEFAULT_REGION'])

        a = AsyncException()
        l = LambdaAsyncResponse(boto_session=boto_session)
        # s = SnsAsyncResponse()
        s = SnsAsyncResponse(arn="arn:abc:def", boto_session=boto_session)

payload = json.dumps(message).encode('utf-8')
        if len(payload) > LAMBDA_ASYNC_PAYLOAD_LIMIT: # pragma: no cover
            raise AsyncException("Payload too large for SNS")
        self.response = self.client.publish(
                                TargetArn=self.arn,
                                Message=payload
                            )
        self.sent = self.response.get('MessageId')

##
# Aync Routers
##

ASYNC_CLASSES = {
    'lambda': LambdaAsyncResponse,
    'sns': SnsAsyncResponse,
}


def route_lambda_task(event, context):
    """
    Deserialises the message from event passed to zappa.handler.run_function
    imports the function, calls the function with args
    """
    message = event
    return run_message(message)


def route_sns_task(event, context):
    """
    Gets SNS Message, deserialises the message,
    imports the function, calls the function with args