==================
Can parse subquery
==================

SELECT id
FROM foo
WHERE id < (
  SELECT id
  FROM bar
  LIMIT 1);

---

(program
 (statement
  (select
   (keyword_select)
   (select_expression
    (field (identifier))))
  (from
   (keyword_from)
   (table_expression (identifier))
   (where
    (keyword_where)
    (where_expression
     (predicate
      (field (identifier))
      (subquery
       (select
        (keyword_select)
        (select_expression
         (field (identifier))))
       (from
        (keyword_from)
        (table_expression (identifier))
        (limit (keyword_limit) (literal))))))))))
