{"ast_node_type":"other","tokens":[{"end":87,"kind":"keyword","start":0,"text":"//"}]}
    // we don't actually create a universe until we see a bound var we have to replace.
    // The `UniverseIndex` of the binding levels above us. These are optional, since we are lazy:
    universe_indices: &'a mut Vec<Option<ty::UniverseIndex>>,