anchor.diff:        SparkPreferences prefs) : super._create(aceManager, file, prefs);
   
     void customizeSession(ace.EditSession session) {
  +    super.customizeSession(session);
  +
       // Go files use hard tabs for indentation.
       session.useSoftTabs = false;
  -    session.tabSize = 4;
     }
   }
   
  
positive.code:       SparkPreferences prefs) : super._create(aceManager, file, prefs);
  
    void customizeSession(ace.EditSession session) {
      // Yaml files use 2-space soft tabs for indentation.
      session.tabSize = 2;
      session.useSoftTabs = true;
    }
  
negative.code: 
      prefs.getValue('fontSize').then((String pref) {
        try {
          if (pref != null) {
            _value = num.parse(pref);
            aceManager.setFontSize(_value);
            _updateLabel(_value);
          }
        } catch (e) {
  
        }
  