anchor.diff:    ListViewCell treeViewCellForNode(TreeView view, String nodeUid) {
       Resource resource = _filesMap[nodeUid];
       if (resource == null) {
  -      print('no resource for ${nodeUid}');
  -      assert(resource != null);
  +      _logger.warning('no resource for ${nodeUid}');
  +      return null;
       }
       FileItemCell cell = new FileItemCell(resource);
       if (resource is Folder) {
  
positive.code: import '../preferences.dart' as preferences;
  import '../scm.dart';
  import '../workspace.dart';
  
  /**
   * An event that is sent to indicate the user would like to select a given
  
negative.code: import 'dart:html' as html;
  
  import 'package:bootjack/bootjack.dart' as bootjack;
  import 'package:logging/logging.dart';
  
  import 'html_utils.dart';
  import 'widgets/file_item_cell.dart';
  