in index.js [159:178]
function createDynamoDataItem(record) {
    var output = {};
    output.Keys = record.dynamodb.Keys;
    if (record.dynamodb.NewImage)
        output.NewImage = record.dynamodb.NewImage;
    if (record.dynamodb.OldImage)
        output.OldImage = record.dynamodb.OldImage;
    // add the sequence number and other metadata
    output.SequenceNumber = record.dynamodb.SequenceNumber;
    output.SizeBytes = record.dynamodb.SizeBytes;
    output.ApproximateCreationDateTime = record.dynamodb.ApproximateCreationDateTime;
    output.eventName = record.eventName;
    // adding userIdentity, used by DynamoDB TTL to indicate removal by TTL as
    // opposed to user initiated remove
    output.userIdentity = record.userIdentity;
    return output;
}