SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 3)
    Literal NULL
    Function isConstant (children 1)
     ExpressionList (children 1)
      Literal NULL
    Asterisk
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (alias a) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 1)
           Literal UInt64_2 (alias x)
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      Subquery (alias b) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 2)
           Literal NULL
           Literal UInt64_3 (alias y)
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier y
        Identifier x