code: public static <ItemT extends HasDocID> BinaryErrorLogger<ItemT, ItemT> forStringifierAndOutputDir(
        Function<? super ItemT, String> stringifier, File outputDirectory) {
      outputDirectory.mkdirs();
      return new BinaryErrorLogger<ItemT, ItemT>(outputDirectory, stringifier, stringifier);
    }
docs: Creates a {@code BinaryErrorLogger}.  The {@code stringifier} is a means of rendering the
  aligned items as strings.  If you don't care, choose {@link Functions#toStringFunction()}.