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packages/intl/lib/extract_messages.dart

 // Copyright (c) 2013, 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.
 
 /**
  * This is for use in extracting messages from a Dart program
  * using the Intl.message() mechanism and writing them to a file for
  * translation. This provides only the stub of a mechanism, because it
  * doesn't define how the file should be written. It provides an
  * [IntlMessage] class that holds the extracted data and [parseString]
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    */
   final String message;
 
   /**
    * Creates a new exception with an optional error [message].
    */
   const IntlMessageExtractionException([this.message = ""]);
 
   String toString() => "IntlMessageExtractionException: $message";
 }