sclass Scorer {
  double score, total;
  
  void addZeroToOne(double score) {
    ++total;
    this.score += clamp(score, 0, 1);
  }
  
  void addZeroToOneError(double error) {
    addZeroToOne(1-error);
  }
  
  void add(bool correct) {
    ++total;
    if (correct) ++score;
  }
  
  void print() {
    main.print(toString());
  }
  
  toString {
    ret formatDouble(ratioToPercent_floor(score, total), 1) + "% correct (n=" + total + ")";
  }
}