@Override
  public void addListener(PromiseListener<Tuple2<T1, T2>> listener) {
    _task.addListener(listener);
  }
@Override
  public void addListener(PromiseListener<Tuple2<T1, T2>> listener) {
    _task.addListener(listener);
  }
@ Override public void addListener ( PromiseListener < Tuple2 < T1 , T2 > > listener ) { _task . addListener ( listener ) ; }
{@inheritDoc}
{