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