public INDArray meanSquaredError(INDArray label, INDArray predictions, INDArray weights,
      LossReduce lossReduce) {
    NDValidation.validateNumerical("meanSquaredError", "label", label);
    NDValidation.validateNumerical("meanSquaredError", "predictions", predictions);
    NDValidation.validateNumerical("meanSquaredError", "weights", weights);