SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function tupleElement (children 1)
     ExpressionList (children 3)
      Function materialize (children 1)
       ExpressionList (children 1)
        Literal Tuple_(\'hello\', \'world\')
      Literal \'xzy\'
      Function array (children 1)
       ExpressionList (children 1)
        Function tuple (children 1)
         ExpressionList (children 2)
          Function array (children 1)
           ExpressionList (children 1)
            Literal \'a\'
          Literal UInt64_1
