docs: public static long current(Context context, String tag) {
          Long appRxValue = sReceivedBytes.get(tag);
          Long appTxValue = sSendBytes.get(tag);
          if (appRxValue == null || appTxValue == null) {
              if (DEBUG) {
                  LogUtils.w(TAG, "current() appRxValue or appTxValue is null.");
              }
              return 0;
          }
          final int uid = getUid(context);
          long appRxValue2 = TrafficStats.getUidRxBytes(uid);
          long appTxValue2 = TrafficStats.getUidTxBytes(uid);
          long rxValue = appRxValue2 - appRxValue;
          long txValue = appTxValue2 - appTxValue;
          if (DEBUG) {
              LogUtils.v(TAG, "current() rxValue=" + rxValue / 1000 + " txValue=" + txValue / 1000 + " uid=" + uid);
          }
          return rxValue;
  
      }