code: private Node tryFoldArithmeticOp(Node n, Node left, Node right) {
      Node result = performArithmeticOp(n.getToken(), left, right);
      if (result != null) {
        result.useSourceInfoIfMissingFromForTree(n);
        reportChangeToEnclosingScope(n);
        n.replaceWith(result);
        return result;
      }
      return n;
    }
docs: Try to fold arithmetic binary operators