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 toFixedString (children 1)
         ExpressionList (children 2)
          Literal \'a\'
          Literal UInt64_1
        Function materialize (children 1)
         ExpressionList (children 1)
          Literal \'b\'
        Function materialize (children 1)
         ExpressionList (children 1)
          Function toFixedString (children 1)
           ExpressionList (children 2)
            Literal \'c\'
            Literal UInt64_1
      Literal \'abc\'