}

  /**
   * Returns a larger power of 2 hashtable size given the current mask.
   *
   * <p>For hashtable sizes less than or equal to 32, the returned power of 2 is 4x the current
   * hashtable size to reduce expensive rehashing. Otherwise the returned power of 2 is 2x the
   * current hashtable size.
   */
  static int newCapacity(int mask) {
    return ((mask < 32) ? 4 : 2) * (mask + 1);
  }

Let's start with an example and then see it in detail.

We create an async function `lifespan()` with `yield` like this:

{* ../../docs_src/events/tutorial003.py hl[16,19] *}

  }

  /**
   * Returns a larger power of 2 hashtable size given the current mask.
   *
   * <p>For hashtable sizes less than or equal to 32, the returned power of 2 is 4x the current
   * hashtable size to reduce expensive rehashing. Otherwise the returned power of 2 is 2x the
   * current hashtable size.
   */
  static int newCapacity(int mask) {
    return ((mask < 32) ? 4 : 2) * (mask + 1);
  }

 * of the <i>next</i> request. I.e., if an expensive task arrives at an idle RateLimiter, it will be
 * granted immediately, but it is the <i>next</i> request that will experience extra throttling,
 * thus paying for the cost of the expensive task.
 *
 * @author Dimitris Andreou
 * @since 13.0
 */

// simply converts positional arguments to NewReader() into a
// more flexible way to provide optional inputs. This is currently
// used by the FanOut API call mostly to disable expensive md5sum
// calculation repeatedly under hash.Reader.
type Options struct {
	MD5Hex     string
	SHA256Hex  string
	Size       int64
	ActualSize int64
	DisableMD5 bool
	ForceMD5   []byte
}

     * Holder object for values that cannot be null or empty (will be printed unconditionally). This
     * helps to shortcut most calls to isEmpty(), which is important because the check for emptiness
     * is relatively expensive. Use a subtype so this also doesn't need any extra storage.
     */
    private static final class UnconditionalValueHolder extends ValueHolder {}
  }

  private MoreObjects() {}

 * of the <i>next</i> request. I.e., if an expensive task arrives at an idle RateLimiter, it will be
 * granted immediately, but it is the <i>next</i> request that will experience extra throttling,
 * thus paying for the cost of the expensive task.
 *
 * @author Dimitris Andreou
 * @since 13.0
 */

    CountingRemovalListener<Integer, Integer> removalListener = countingRemovalListener();
    IdentityLoader<Integer> loader = identityLoader();

    // Even numbers are free, odd are too expensive
    Weigher<Integer, Integer> evensOnly =
        new Weigher<Integer, Integer>() {
          @Override
          public int weigh(Integer k, Integer v) {
            return k % 2;
          }
        };

    int removes = frequency(asList(stimuli), remove);
    if ((!features.contains(IteratorFeature.SUPPORTS_REMOVE) && removes > 1)
        || (stimuli.length >= 5 && removes > 2)) {
      // removes are the most expensive thing to test, since they often throw exceptions with stack
      // traces, so we test them a bit less aggressively
      return;
    }

  }

  /**
   * Returns an immutable <i>view</i> of this array's values as a {@code List}; note that {@code
   * long} values are boxed into {@link Long} instances on demand, which can be very expensive. The
   * returned list should be used once and discarded. For any usages beyond that, pass the returned
   * list to {@link com.google.common.collect.ImmutableList#copyOf(Collection) ImmutableList.copyOf}