Function country_of

pub fn country_of(
    catalog: &Catalog,
    held: &Sources,
    artist: Id,
) -> Option<String>

The country an artist is from, as the layer holds it.

None covers three quite different things — never fetched, fetched and MusicBrainz has no area, or matched to nobody — and callers that need to tell them apart read the record itself. What they share is that this program cannot say where the artist is from, which is what a filter needs.