anchor.diff:    'unsubscribeFromFriendStatus': (int id, Function handleStatusChange) => handleStatusChange({'isOnline': false}),
   };
   
  +// Custom Hook
   StateHook useFriendStatus(friendID) {
     final isOnline = useState(false);
   
  
positive.code:           }, []),
            react.br({'key': 'br4'}),
            react.h2({'key': 'useDebugValueTestLabel'}, ['useDebugValue Hook Test']),
            FriendListItem({
              'friend': {'id': 1, 'name': 'user 1'}
            }, []),
            FriendListItem({
              'friend': {'id': 2, 'name': 'user 2'}
            }, []),
            FriendListItem({
              'friend': {'id': 3, 'name': 'user 3'}
            }, []),
            FriendListItem({
              'friend': {'id': 4, 'name': 'user 4'}
            }, []),
          ]),
          querySelector('#content'));
  
negative.code:   return isOnline;
  }
  
  var FriendListItem = react.registerFunctionComponent((Map props) {
    final isOnline = useFriendStatus(props['friend']['id']);
  
    return react.li({
  