docs: public static DiscreteFactor normalizeVariance(DiscreteFactor featureFactor, int featureVariableNum) {
      DiscreteFactor variance = getVariances(featureFactor, featureVariableNum);
      DiscreteFactor stdDev = new TableFactor(variance.getVars(), variance.getWeights().elementwiseSqrt());
  
      return featureFactor.product(stdDev.inverse());
    }