private static TimeUnit chooseUnit(long nanos) {
        if (DAYS.convert(nanos, NANOSECONDS) > 0) {
            return DAYS;
        }
        if (HOURS.convert(nanos, NANOSECONDS) > 0) {
            return HOURS;
        }
        if (MINUTES.convert(nanos, NANOSECONDS) > 0) {
            return MINUTES;
        }
        if (SECONDS.convert(nanos, NANOSECONDS) > 0) {
            return SECONDS;
        }
        if (MILLISECONDS.convert(nanos, NANOSECONDS) > 0) {
            return MILLISECONDS;
        }
        if (MICROSECONDS.convert(nanos, NANOSECONDS) > 0) {
            return MICROSECONDS;
        }
        return NANOSECONDS;
    }
Returns a string representation of the current elapsed time.
lts-core/src/main/java/com/github/ltsopensource/core/commons/concurrent/limiter/Stopwatch.java