Rendeding labels for DOT graphs on playground does not work

[LunaticMuch]

I am making few tests using the playground for DOT language.

All works, but how about this example for data structures coming directly from GraphVIZ? I would expect it works, but in fact it does not work. There's probably an issue with the example itself, as the node should be ellipse which I think can't render with fields, but removing it, I get nothing.

So I am wondering if the library supports the concept of fields in a node, either directly or as part of DOT language. I would expect to be supported with DOT language, but seems not.