/**
* constructs a new fronier instance which will be linked to the tasks queue
* and the specified server queue list, so the frontier will schedule it's tasks
* between the servers
*/
public RankFrointer(Queue <Url> tasksQueue, List <Queue <Url> > serversQueues)
: base(tasksQueue, serversQueues)
{
_rankingTrie = new RankingTrie();
}