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

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

--------------------------------------------------------------------------------

(program
  (statement
    (select
      (keyword_select)
      (select_expression
        (term
          (field
            (identifier)))))
    (from
      (keyword_from)
      (relation
        (object_reference
          (identifier)))
      (where
        (keyword_where)
        (binary_expression
          (field
            (identifier))
          (subquery
            (select
              (keyword_select)
              (select_expression
                (term
                  (field
                    (identifier)))))
            (from
              (keyword_from)
              (relation
                (object_reference
                  (identifier)))
              (limit
                (keyword_limit)
                (literal)))))))))
