presto-parser/src/main/java/io/prestosql/sql/tree/ExpressionTreeRewriter.java/ExpressionTreeRewriter/visitSubscriptExpression
class ExpressionTreeRewriter:        @Override
        protected Expression visitSubscriptExpression(SubscriptExpression node, Context<C> context)
        {
            if (!context.isDefaultRewrite()) {
                Expression result = rewriter.rewriteSubscriptExpression(node, context.get(), ExpressionTreeRewriter.this);
                if (result != null) {
                    return result;
                }
            }

            Expression base = rewrite(node.getBase(), context.get());
            Expression index = rewrite(node.getIndex(), context.get());

            if (base != node.getBase() || index != node.getIndex()) {
                return new SubscriptExpression(base, index);
            }

            return node;
        }