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