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packages/html/lib/src/css_class_set.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // TODO(jmesserly): everything in this file is copied straight from "dart:html".
 library html.dom.src;
 
 import 'dart:collection';
 import 'package:html/dom.dart';
 
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    */
   Set<String> readClasses();
 
   /**
    * Join all the elements of a set into one string and write
    * back to the element.
    * This is intended to be overridden by specific implementations.
    */
   void writeClasses(Set<String> s);
 }