presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/visitSubscript
class AstBuilder:    @Override
    public Node visitSubscript(SqlBaseParser.SubscriptContext context)
    {
        return new SubscriptExpression(getLocation(context), (Expression) visit(context.value), (Expression) visit(context.index));
    }