docs: public String getDescription(int numDigits) {
      StringBuffer sb = new StringBuffer();
      sb.append("--- PR Stats ---").append("\n");
      for (L label : labelIndex) {
        if (label.equals(negLabel)) { continue; }      
        sb.append("** ").append(label.toString()).append(" **\n");
        sb.append("\tPrec:   ").append(getPrecisionDescription(numDigits, label)).append("\n");
        sb.append("\tRecall: ").append(getRecallDescription(numDigits, label)).append("\n");
        sb.append("\tF1:     ").append(getF1Description(numDigits, label)).append("\n");
      }
      sb.append("** Overall **\n");
      sb.append("\tPrec:   ").append(getPrecisionDescription(numDigits)).append("\n");
      sb.append("\tRecall: ").append(getRecallDescription(numDigits)).append("\n");
      sb.append("\tF1:     ").append(getF1Description(numDigits));
      return sb.toString();
    }