code: public static void d(ISubsystem subsystem, String tag, String pattern, Object... parameters) {
          if (!isEnabled(subsystem)) return;
          d(subsystem, tag, format(pattern, parameters));
      }
docs: Send a DEBUG 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 pattern The message pattern
  @return