text: public override sealed Explanation Explain(BasicStats stats, float tfn){Explanation result = new Explanation();result.Description = this.GetType().Name + ", computed from: ";result.Value = Score(stats, tfn);result.AddDetail(new Explanation(tfn, "tfn"));result.AddDetail(new Explanation(stats.TotalTermFreq, "totalTermFreq"));result.AddDetail(new Explanation(stats.DocFreq, "docFreq"));return result;}