SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function equals (children 1)
     ExpressionList (children 2)
      Function concat (children 1)
       ExpressionList (children 3)
        Function materialize (children 1)
         ExpressionList (children 1)
          Literal \'a\'
        Function materialize (children 1)
         ExpressionList (children 1)
          Function toFixedString (children 1)
           ExpressionList (children 2)
            Literal \'b\'
            Literal UInt64_1
        Function toFixedString (children 1)
         ExpressionList (children 2)
          Literal \'c\'
          Literal UInt64_1
      Literal \'abc\'