{"ast_node_type":"variable","tokens":[{"end":42,"kind":"keyword","start":0,"text":"let"}]}
        let res_def_id = match expr.kind {
    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
            hir::ExprKind::Path(hir::QPath::Resolved(_, path)) => path.res.opt_def_id(),