SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 4)
   ExpressionList (children 1)
    Function arraySplit (children 1)
     ExpressionList (children 2)
      Function lambda (children 1)
       ExpressionList (children 2)
        Function tuple (children 1)
         ExpressionList (children 1)
          Identifier x
        Literal UInt64_0
      Function array (children 1)
       ExpressionList
   Function materialize (children 1)
    ExpressionList (children 1)
     Literal UInt64_1
   ExpressionList (children 1)
    Function tuple (children 1)
     ExpressionList (children 2)
      Literal UInt64_0
      Function ignore (children 1)
       ExpressionList (children 1)
        Literal \'a\'
   Set
