code: public static Guid combine(Guid... guids) throws IOException {
      byte[][] byteArrays = new byte[guids.length][];
      for (int i = 0; i < guids.length; i++) {
        byteArrays[i] = guids[i].sha;
      }
      return fromByteArrays(byteArrays);
    }
docs: Combine multiple {@link Guid}s into a single {@link Guid}.
  @throws IOException