code: private Integer getChannelForSymbol(final BitfinexStreamSymbol symbol) {
  		synchronized (channelIdToHandlerMap) {
  			return channelIdToHandlerMap.values()
  					.stream()
  					.filter(v -> Objects.equals(v.getSymbol(), symbol))
  					.map(ChannelCallbackHandler::getChannelId)
  					.findFirst().orElse(null);
  		}
  	}
docs: Find the channel for the given symbol
  @param symbol
  @return