SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function mapFromArrays (children 1)
     ExpressionList (children 2)
      Function materialize (children 1)
       ExpressionList (children 1)
        Function map (children 1)
         ExpressionList (children 4)
          Literal UInt64_1
          Literal \'a\'
          Literal UInt64_2
          Literal \'b\'
      Function materialize (children 1)
       ExpressionList (children 1)
        Function array (children 1)
         ExpressionList (children 2)
          Literal \'c\'
          Literal \'d\'