docs: @Override public void lcompute() {
      _ok = new int[_files.length][H2O.CLOUD.size()];
      for (int i = 0; i < _files.length; ++i) {
        File f = new File(_files[i]);
        if (f.exists() && (f.length()==_sizes[i]))
          _ok[i][H2O.SELF.index()] = 1;
      }
      tryComplete();
    }