{"ast_node_type":"variable","tokens":[{"end":66,"kind":"keyword","start":0,"text":"let"}]}
                let r_succ = self.propagate_through_expr(r, succ);
            hir::ExprKind::Index(ref l, ref r, _) | hir::ExprKind::Binary(_, ref l, ref r) => {
                self.propagate_through_expr(l, r_succ)