/** Poor man's method reference for {@code Deque::addFirst} and {@code Deque::addLast}. */
  private enum InsertionOrder {
    FRONT {
      @Override
      <T> void insertInto(Deque<T> deque, T value) {
        deque.addFirst(value);
      }
    },
    BACK {
      @Override
      <T> void insertInto(Deque<T> deque, T value) {
        deque.addLast(value);
      }
    };

     *            A disposable resource. Must not be {@literal null}.
     */
    public static synchronized void add(final Disposable disposable) {
        assertArgumentNotNull("disposable", disposable);
        disposables.addLast(disposable);
    }

    /**
     * Registers a disposable resource at the beginning.
     * <p>

    Deque<NodeAndRemainingSuccessors<N>> stack = new ArrayDeque<>();
    stack.addLast(new NodeAndRemainingSuccessors<>(startNode));

    while (!stack.isEmpty()) {
      // To peek at the top two items, we need to temporarily remove one.
      NodeAndRemainingSuccessors<N> top = stack.removeLast();
      NodeAndRemainingSuccessors<N> prev = stack.peekLast();
      stack.addLast(top);

      N node = top.node;

        if (state.set) {
          return java.util.Optional.of(state.get());
        }
        // fall back to the last split
        continue;
      }
      splits.addLast(prefix);
      splits.addLast(spliterator);
    }
    return java.util.Optional.empty();
  }

  /**
   * Returns the last element of the specified stream, or {@link OptionalInt#empty} if the stream is
   * empty.
   *

        if (state.set) {
          return java.util.Optional.of(state.get());
        }
        // fall back to the last split
        continue;
      }
      splits.addLast(prefix);
      splits.addLast(spliterator);
    }
    return java.util.Optional.empty();
  }

  /**
   * Returns the last element of the specified stream, or {@link OptionalInt#empty} if the stream is
   * empty.
   *

    TestSuite suite = new TestSuite(name);
    for (Entry<String, String> entry : TEST_STRINGS.entrySet()) {
      if (testAsCharSource) {
        suite.addTest(suiteForString(factory, entry.getValue(), name, entry.getKey()));
      } else {
        suite.addTest(
            suiteForBytes(factory, entry.getValue().getBytes(UTF_8), name, entry.getKey(), true));
      }
    }
    return suite;
  }

    TestSuite suite = new TestSuite(name);
    for (Entry<String, String> entry : TEST_STRINGS.entrySet()) {
      if (testAsCharSource) {
        suite.addTest(suiteForString(factory, entry.getValue(), name, entry.getKey()));
      } else {
        suite.addTest(
            suiteForBytes(factory, entry.getValue().getBytes(UTF_8), name, entry.getKey(), true));
      }
    }
    return suite;
  }

  @J2ktIncompatible
  @GwtIncompatible // suite
  @AndroidIncompatible // test-suite builders
  public static Test suite() {
    TestSuite suite = new TestSuite();

    suite.addTest(
        SetTestSuiteBuilder.using(new ImmutableSetCopyOfGenerator())
            .named(ImmutableSetTest.class.getName())
            .withFeatures(
                CollectionSize.ANY,

    suite.addTest(
        SetTestSuiteBuilder.using(new ImmutableSetWithBadHashesGenerator())
            .named(ImmutableSetTest.class.getName() + ", with bad hashes")
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .createTestSuite());

    suite.addTest(

      suite.addTest(stringSuite);
    }
    return suite;
  }

  static TestSuite suiteForString(
      String name, CharSinkFactory factory, String string, String desc) {
    TestSuite stringSuite = new TestSuite(name + " [" + desc + "]");
    for (Method method : testMethods) {
      stringSuite.addTest(new CharSinkTester(factory, string, name, desc, method));
    }