TreeTraversal.GuidedIt.Guide<T> createChildrenGuide(final T parent) {
      return new TreeTraversal.GuidedIt.Guide<T>() {
        final Condition<? super T> expand = buildExpandConditionForChildren(parent);
        @Override
        public void guide(@NotNull TreeTraversal.GuidedIt<T> guidedIt) {
          doPerformChildrenGuidance(guidedIt, expand);
        }
      };
    }
TreeTraversal.GuidedIt.Guide<T> createChildrenGuide(final T parent)