SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function equals (children 1)
     ExpressionList (children 2)
      Function format (children 1)
       ExpressionList (children 3)
        Literal \'{}{}\'
        Function materialize (children 1)
         ExpressionList (children 1)
          Literal \'a\'
        Function materialize (children 1)
         ExpressionList (children 1)
          Literal \'b\'
      Literal \'ab\'