SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 2)
    Function materialize (alias x) (children 1)
     ExpressionList (children 1)
      Function array (children 1)
       ExpressionList (children 1)
        Function toNullable (children 1)
         ExpressionList (children 1)
          Literal UInt64_1
    Function arrayElementOrNull (alias y) (children 1)
     ExpressionList (children 2)
      Identifier x
      Function toNullable (children 1)
       ExpressionList (children 1)
        Literal UInt64_1
