SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function countSubstrings (children 1)
     ExpressionList (children 2)
      Literal \'aaa\'
      Function materialize (children 1)
       ExpressionList (children 1)
        Literal \'\'