docs: public static void normalize(double[] doubles, double sum) {
  
      if (Double.isNaN(sum)) {
        throw new IllegalArgumentException("Can't normalize array. Sum is NaN.");
      }
      if (sum == 0) {
        // Maybe this should just be a return.
        throw new IllegalArgumentException("Can't normalize array. Sum is zero.");
      }
      for (int i = 0; i < doubles.length; i++) {
        doubles[i] /= sum;
      }
    }