/** {@inheritDoc} */
    @Override
    public String reduce(List<GridComputeJobResult> results) throws GridException {
      int sum = 0;

      String locNodeId = null;

      for (GridComputeJobResult res : results) {
        GridBiTuple<String, Integer> part = res.getData();

        if (locNodeId == null) locNodeId = part.get1();

        Integer i = part.get2();

        if (i != null) sum += i;
      }

      assert gridSize == sum;

      return locNodeId;
    }