* second" (commonly referred to as <i>QPS</i>, queries per second), and a <i>warmup period</i>,
   * during which the {@code RateLimiter} smoothly ramps up its rate, until it reaches its maximum
   * rate at the end of the period (as long as there are enough requests to saturate it). Similarly,
   * if the {@code RateLimiter} is left <i>unused</i> for a duration of {@code warmupPeriod}, it

    for (int i = 0; i < 8; i++) {
      limiter.acquire(); // // #1
    }
    stopwatch.sleepMillis(4500); // #2: back to cold state (warmup period + repay last acquire)
    for (int i = 0; i < 3; i++) { // only three steps, we're somewhere in the warmup period
      limiter.acquire(); // #3
    }

    limiter.setRate(4.0); // double the rate!

  }

  @Override
  public final ScheduledFuture<?> scheduleAtFixedRate(
      Runnable command, long initialDelay, long period, TimeUnit unit) {
    return delegate.scheduleAtFixedRate(wrapTask(command), initialDelay, period, unit);
  }

  @Override
  public final ScheduledFuture<?> scheduleWithFixedDelay(
      Runnable command, long initialDelay, long delay, TimeUnit unit) {

    for (int i = 0; i < 8; i++) {
      limiter.acquire(); // // #1
    }
    stopwatch.sleepMillis(4500); // #2: back to cold state (warmup period + repay last acquire)
    for (int i = 0; i < 3; i++) { // only three steps, we're somewhere in the warmup period
      limiter.acquire(); // #3
    }

    limiter.setRate(4.0); // double the rate!

   * of the function, thus time. Thus, the RateLimiter becomes /faster/ after a period of
   * underutilization. If, on the other hand, we pick a function that goes /above/ that horizontal
   * line, then it means that the area (time) is increased, thus storedPermits are more costly than
   * fresh permits, thus the RateLimiter becomes /slower/ after a period of underutilization.
   *

      return 0;
    }
  }

  @Override
  public ListenableScheduledFuture<?> scheduleAtFixedRate(
      Runnable command, long initialDelay, long period, TimeUnit unit) {
    throw new UnsupportedOperationException("scheduleAtFixedRate is not supported.");
  }

  @Override
  public ListenableScheduledFuture<?> scheduleWithFixedDelay(

      return NeverScheduledFuture.create();
    }

    @Override
    public ListenableScheduledFuture<?> scheduleAtFixedRate(
        Runnable command, long initialDelay, long period, TimeUnit unit) {
      return NeverScheduledFuture.create();
    }

    @Override
    public ListenableScheduledFuture<?> scheduleWithFixedDelay(

    @Override
    public ScheduledFuture<?> scheduleAtFixedRate(
        Runnable command, long initialDelay, long period, TimeUnit unit) {
      assertThat(command).isInstanceOf(WrappedRunnable.class);
      lastMethodCalled = "scheduleAtFixedRate";
      lastInitialDelay = initialDelay;
      lastDelay = period;
      lastUnit = unit;
      return null;
    }

    @Override

     * @param initialDelay the time to delay first execution
     * @param period the period between successive executions of the task
     * @param unit the time unit of the initialDelay and period parameters
     */
    @SuppressWarnings("GoodTime") // should accept a java.time.Duration
    public static Scheduler newFixedRateSchedule(
        final long initialDelay, final long period, final TimeUnit unit) {
      checkNotNull(unit);

      return 0;
    }
  }

  @Override
  public ListenableScheduledFuture<?> scheduleAtFixedRate(
      Runnable command, long initialDelay, long period, TimeUnit unit) {
    throw new UnsupportedOperationException("scheduleAtFixedRate is not supported.");
  }

  @Override
  public ListenableScheduledFuture<?> scheduleWithFixedDelay(