return servers.remove(category) != null;
Object o = servers.get(category); if (o == null) { return false; } if (o instanceof Set) { Set equivalents = (Set)o; return equivalents.remove(subordinate); } else {  if (o != subordinate) { return false; } servers.remove(category); return true; }
   public boolean unregister(Serializable category)   {      synchronized(servers)      {         return servers.remove(category) != null;      }   }