Create an example of a serializer

Create an example that implements a serializer.

+ Use version mark/metadata, so the serializer has two different behaviors.
+ Show how it can be used to persist data.
+ Show an example with XML serializer too.

No file, test, or entry point is named. Start by locating the repository's existing examples and serializer APIs, then determine where this example belongs. Done means the example demonstrates version metadata with two behaviors, persistence, and an XML serializer.

Scritto dal modello di indicizzazione a partire dal testo della issue.