{"ast_node_type":"variable","tokens":[{"end":73,"kind":"keyword","start":0,"text":"let"}]}
        let DefKind::Fn = tcx.def_kind(this_fi.owner_id) else { return };
    fn check_foreign_item<'tcx>(&mut self, tcx: TyCtxt<'tcx>, this_fi: hir::ForeignItemId) {
        let Some(existing_did) = self.insert(tcx, this_fi) else { return };