docs: public double getQuantile(final double fraction) {
      if (isEmpty()) { return Double.NaN; }
      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 getMinValue(); }
      else if (fraction == 1.0) { return getMaxValue(); }
      else {
        final DoublesAuxiliary aux = new DoublesAuxiliary(this);
        return aux.getQuantile(fraction);
      }
    }