code: public boolean removeTickCallback(final BitfinexTickerSymbol symbol,
  			final BiConsumer<BitfinexTickerSymbol, BitfinexTick> callback) throws BitfinexClientException {
  
  		return tickerCallbacks.removeCallback(symbol, callback);
  	}
docs: Remove the a tick callback
  @param symbol
  @param callback
  @return
  @throws BitfinexClientException