SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Subquery (alias bar) (children 1)
     SelectWithUnionQuery (children 1)
      ExpressionList (children 1)
       SelectQuery (children 1)
        ExpressionList (children 1)
         Function toLowCardinality (children 1)
          ExpressionList (children 1)
           Literal \'a\'
   ExpressionList (children 1)
    Identifier bar