How to use the zappa.asynchronous.LambdaAsyncResponse 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)

message['command'] = 'zappa.asynchronous.route_sns_task'
        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,

def _send(self, message):
        """
        Given a message, directly invoke the lamdba function for this task.
        """
        message['command'] = 'zappa.asynchronous.route_lambda_task'
        payload = json.dumps(message).encode('utf-8')
        if len(payload) > LAMBDA_ASYNC_PAYLOAD_LIMIT: # pragma: no cover
            raise AsyncException("Payload too large for async Lambda call")
        self.response = self.client.invoke(
                                    FunctionName=self.lambda_function_name,
                                    InvocationType='Event', #makes the call async
                                    Payload=payload
                                )
        self.sent = (self.response.get('StatusCode', 0) == 202)

class SnsAsyncResponse(LambdaAsyncResponse):
    """
    Send a SNS message to a specified SNS topic
    Serialise the func path and arguments
    """
    def __init__(self, lambda_function_name=None, aws_region=None, capture_response=False, **kwargs):

        self.lambda_function_name = lambda_function_name
        self.aws_region = aws_region

        if kwargs.get('boto_session'):
            self.client = kwargs.get('boto_session').client('sns')
        else: # pragma: no cover
            self.client = SNS_CLIENT


        if kwargs.get('arn'):