docs: public T getQuantile(final double fraction) {
      if ((fraction < 0.0) || (fraction > 1.0)) {
        throw new SketchesArgumentException("Fraction cannot be less than zero or greater than 1.0");
      }
      if      (fraction == 0.0) { return minValue_; }
      else if (fraction == 1.0) { return maxValue_; }
      else {
        final ItemsAuxiliary<T> aux = constructAuxiliary();
        return aux.getQuantile(fraction);
      }
    }