anchor.diff:  import "dart:mirrors";
   
   class localStorage {
  -  Storage _localStorage;
  -
  -  localStorage() {
  -    if (chrome.storage != null) {
  -      _localStorage = chrome.storage.local;
  -    // for dartium
  -    } else {
  -      _localStorage = window.localStorage;
  -    }
  -  }
   
     String _key(dynamic key) {
       if (key is! String) {
  
positive.code:     String normalized_key = _key(key);
      if (chrome.storage != null ) {
        Completer completer = new Completer();
        _localStorage.get([normalized_key]).then((Map<String,String> values) {
          var result;
          var value = values[normalized_key];
          if (value == null) {
  
negative.code:     }
    }
  
    void set(dynamic key, dynamic value) {
      String normalized_key = _key(key);
      String normalized_value = JSON.encode(value);
      if (chrome.storage != null) {
        chrome.storage.local.set({normalized_key: normalized_value});
      // for dartium
      } else {
        window.localStorage.set(normalized_key, normalized_value);
  