anchor.diff:    Map attribute_callbacks = {
       'default'  : (attr_name, self) => self.attribute_callbacks_collection['write_property_to_dom'](attr_name, self),
       'disabled' : (attr_name, self) {
  -      if(self.disabled == 'disabled') {
  -        self.event_locks.add(#any); 
  +      if(self.disabled) {
  +        self.event_locks.add(#any);
           self.behave('disable');
         } else {
           self.behave('enable');
  
positive.code: 
      this.options = new LinkedHashMap.from(parsed_json);
    }
    
    /** This methd is called not once, but every time we fetch new options from the server,
      * because the newly added option elements are not being monitored by the previously
      * created listener.
  
negative.code:           break;
        }
        e.preventDefault();
      }
    }
  
    void _addFetchUrlParam(String name, String value) {
  