* Returns the identity function.
   *
   * <p><b>Discouraged:</b> Prefer using a lambda like {@code v -> v}, which is shorter and often
   * more readable.
   */
  // implementation is "fully variant"; E has become a "pass-through" type
  @SuppressWarnings("unchecked")
  public static <E extends @Nullable Object> Function<E, E> identity() {
    return (Function<E, E>) IdentityFunction.INSTANCE;
  }

  // enum singleton pattern

  private enum SupplierFunctionImpl implements SupplierFunction<@Nullable Object> {
    INSTANCE;

    // Note: This makes T a "pass-through type"
    @Override
    public @Nullable Object apply(Supplier<@Nullable Object> input) {
      return input.get();
    }

    @Override
    public String toString() {

   *
   * <p>This method accepts the exact format generated by {@link #toString}. If you require more
   * lenient {@code base 16} decoding, please use {@link com.google.common.io.BaseEncoding#decode}
   * (and pass the result to {@link #fromBytes}).
   *
   * @since 15.0
   */
  public static HashCode fromString(String string) {
    checkArgument(

        ProtwordsItem newItem = new ProtwordsItem(0, "testNew");
        ProtwordsFile.ProtwordsUpdater updater = protwordsFile.new ProtwordsUpdater(newItem);

        // Write an existing item (should pass through)
        ProtwordsItem existingItem = new ProtwordsItem(10, "existing");
        ProtwordsItem result = updater.write(existingItem);

        assertNotNull(result);

 *
 * <ol>
 *   <li>Expose a public method, known as the <i>event subscriber</i>, which accepts a single
 *       argument of the type of event desired;
 *   <li>Mark it with a {@link Subscribe} annotation;
 *   <li>Pass itself to an EventBus instance's {@link #register(Object)} method.
 * </ol>
 *
 * <h2>Posting Events</h2>
 *
 * <p>To post an event, simply provide the event object to the {@link #post(Object)} method. The

    TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
    Future<?> scheduled = executorService.schedule(task, delay, timeUnit);
    /*
     * Even when the user interrupts the task, we pass `false` to `cancel` so that we don't
     * interrupt a second time after the interruption performed by TrustedListenableFutureTask.
     */
    task.addListener(() -> scheduled.cancel(false), directExecutor());

    /**
     * Gets an array of rescorer builders for post-processing search results.
     * This method evaluates all configured query rescorers with the provided parameters.
     *
     * @param params parameters to pass to the rescorers during evaluation
     * @return an array of rescorer builders, filtered to exclude null values
     */
    public RescorerBuilder<?>[] getRescorers(final Map<String, Object> params) {

  }

  /*
   * Whenever an implementation uses `instanceof` on a parameter instance, the test has to know that
   * (so much for "black box") and try instances that both do and don't pass the check. The "don't"
   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(Collection<T> collection) {
    // return collection::iterator;
    return new Iterable<T>() {

     * building for Android): Ensure that any object you pass implements the interface not just in
     * your current SDK version but also at the oldest version you support. For example, <a
     * href="https://developer.android.com/sdk/api_diff/16/">API Level 16</a> is the first version
     * in which {@code Cursor} is {@code Closeable}. To support older versions, pass a wrapper

  }

  /*
   * Whenever an implementation uses `instanceof` on a parameter instance, the test has to know that
   * (so much for "black box") and try instances that both do and don't pass the check. The "don't"
   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(Collection<T> collection) {
    // return collection::iterator;
    return new Iterable<T>() {