text: public final Explanation explain(BasicStats stats) {return Explanation.match(lambda(stats),getClass().getSimpleName()+ ", computed as (F + 1) / (N + 1) from:",Explanation.match(stats.getTotalTermFreq(),"F, total number of occurrences of term across all documents"),Explanation.match(stats.getNumberOfDocuments(),"N, total number of documents with field"));}