code: public static int e(ISubsystem subsystem, String tag, String msg) {
          return isEnabled(subsystem) ?
                  currentLog.e(tag, getMsg(subsystem,msg)) : 0;
      }
docs: Send an ERROR log message with specified subsystem. If subsystem is not enabled the message
  will not be logged
  @param subsystem logging subsystem
  @param tag Used to identify the source of a log message. It usually identifies the class or
  activity where the log call occurs.
  @param msg The message you would like logged.
  @return