code: public FutureOperation unsubscribeTicker(final BitfinexTickerSymbol tickerSymbol) {
  		
  		final FutureOperation future = new FutureOperation(tickerSymbol);
  		pendingUnsubscribes.registerFuture(future);
  
  		lastTickerActivity.remove(tickerSymbol);
  		final UnsubscribeChannelCommand command = new UnsubscribeChannelCommand(tickerSymbol);
  		client.sendCommand(command);
  		
  		return future;
  	}
docs: Unsubscribe a ticker
  @param tickerSymbol
  @return