/// <summary>
 /// Add new entry to emitter.
 /// </summary>
 /// <param name="key"></param>
 /// <param name="count"></param>
 public void Add(string key, RelevanceCount count)
 {
     if (!this.HasKey(key))
     {
         lock (RelevanceEmitter.Lock)
             this.Index.Add(key, new RelevanceEntry(count));
     }
 }
 public RelevanceEntry(RelevanceCount entry)
 {
     this.Entry = entry;
     this.ResetExpiration();
 }