{"ast_node_type":"variable","tokens":[{"end":34,"kind":"keyword","start":0,"text":"let"}]}
        let loc = self.lookup(db);
    ) -> InFile<ArenaMap<la_arena::Idx<ast::UseTree>, Self::Value>> {
        InFile::new(loc.id.file_id, use_tree_source_map(db, loc.id).into_iter().collect())