SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function concat (children 1)
     ExpressionList (children 2)
      Literal UInt64_42
      Function materialize (children 1)
       ExpressionList (children 1)
        Function CAST (children 1)
         ExpressionList (children 2)
          Literal NULL
          Literal \'Nullable(UInt64)\'
