SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 2)
    Function _CAST (alias y) (children 1)
     ExpressionList (children 2)
      Identifier x
      Literal \'UInt8\'
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier y
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Function VALUES (children 1)
       ExpressionList (children 3)
        Literal \'x Nullable(String)\'
        Literal \'123\'
        Literal \'456\'
