docs: public static <E, C extends Counter<E>> double saferL2Norm(C c) {
      double maxVal = 0.0;
      for (E key : c.keySet()) {
        double value = Math.abs(c.getCount(key));
        if (value > maxVal)
          maxVal = value;
      }
      double sqrSum = 0.0;
      for (E key : c.keySet()) {
        double count = c.getCount(key);
        sqrSum += Math.pow(count / maxVal, 2);
      }
      return maxVal * Math.sqrt(sqrSum);
    }