[Wildcard Variables] Core library updates

[kallentu]

This issue tracks any updates we need to do with the core libraries for the wildcard variables feature.

@lrhn Do you have any idea if there's any changes necessary? We can close the issue otherwise.

[lrhn]

Should be nothing we need to do.

I do not expect any public API to change, if anything, we could perhaps use the new feature in some or the example code, but we'd have to go through all of it to check, there are no obvious candidates. And there might not be any place where a _ is better than what we already have