code: public SparseTensor getOldKeyIndicatorTensor() {
      double[] values = new double[oldKeyNums.length];
      Arrays.fill(values, 1.0);
      return SparseTensor.fromUnorderedKeyValues(oldTensor.getDimensionNumbers(), 
          oldTensor.getDimensionSizes(), oldKeyNums, values);
    }
docs: Gets a tensor of indicator variables for the old key values in this. The
  returned tensor has value 1 for all keys in this, and 0 for all other keys.
  
  @return