code: static void handleClientDisconnect(H2ONode client) {
      if(client != H2O.SELF) {
        if (H2O.isFlatfileEnabled()) {
          H2O.removeNodeFromFlatfile(client);
        }
        H2O.removeClient(client);
      }
    }
docs: This method checks whether the client is disconnected from this node due to some problem such as client or network
  is unreachable.