code: public void subscribe(ArrayList<Long> tokens) {
          if(ws != null) {
              if (ws.isOpen()) {
                  createTickerJsonObject(tokens, mSubscribe);
                  ws.sendText(createTickerJsonObject(tokens, mSubscribe).toString());
                  subscribedTokens.addAll(tokens);
                  for(int i = 0; i < tokens.size(); i++){
                      modeMap.put(tokens.get(i), modeQuote);
                  }
              }else {
                  if(onErrorListener != null) {
                      onErrorListener.onError(new KiteException("ticker is not connected", 504));
                  }
              }
          }else {
              if(onErrorListener != null) {
                  onErrorListener.onError(new KiteException("ticker is null not connected", 504));
              }
          }
      }
docs: Subscribes for list of tokens.
  @param tokens is list of tokens to be subscribed for.