class PeerChainTracker {

  public void subscribeToTargetChainUpdates(final Runnable subscriber) {
    chainsUpdatedSubscribers.subscribe(subscriber);
  }

  public  PeerChainTracker(
      final EventThread eventThread,
      final P2PNetwork<Eth2Peer> p2pNetwork,
      final SyncSourceFactory syncSourceFactory,
      final TargetChains finalizedChains,
      final TargetChains nonfinalizedChains);

}