sclass ScoredStringSearcher extends ScoredSearcher_stable<S> {
  Set<S> seen;
  
  *() {}
  *(S query, O... _) { super(query); }
  
  // true = duplicate entries are filtered out
  selfType uniquify(bool b) {
    seen = b ? new Set : null;
    this;
  }
  
  void put aka add(S s) {
    if (seen == null || seen.add(s))
      put(s, s);
  }
  
  void addAll(Iterable<S> l) {
    fOr (s : l) add(s);
  }
  
  void addAll(S... l) { addAll(asList(l)); }
}