handler.python

def handle(event, context):
    output = []

    for record in event['records']:
        payload = base64.b64decode(record['data'])

        result = dropped_or_okay(payload)
        if result == 'Ok':
            payload = preprocess_payload(payload)

        output_record = {
            'recordId': record['recordId'],
            'result': result,
            'data': base64.b64encode(json.dumps(payload).encode("utf-8")).decode("utf-8")
        }
        output.append(output_record)

    return {'records': output}