ReferenceEntry<K, V> next = head.getNextInWriteQueue();
      return (next == head) ? null : next;
    }

    @Override
    public @Nullable ReferenceEntry<K, V> poll() {
      ReferenceEntry<K, V> next = head.getNextInWriteQueue();
      if (next == head) {
        return null;
      }

      remove(next);
      return next;
    }

    @Override

  }

  static int advanceOneBit(int next) {
    if ((next & 1) != 0) {
      return (next >>> 1) ^ CRC32C_GENERATOR_FLIPPED;
    } else {
      return next >>> 1;
    }
  }

  public void testCrc32cStrideTable() {
    int next = CRC32C_GENERATOR_FLIPPED;
    for (int i = 0; i < 12; i++) { // for 3 ints = 12 bytes in between each stride window

      private final StrongKeyStrongValueEntry<K, V> next;

      LinkedStrongKeyStrongValueEntry(K key, int hash, StrongKeyStrongValueEntry<K, V> next) {
        super(key, hash);
        this.next = next;
      }

      @Override
      public StrongKeyStrongValueEntry<K, V> getNext() {
        return next;
      }
    }

    assertThrows(NoSuchElementException.class, iterator::next);
    assertThrows(IllegalStateException.class, iterable::iterator);
  }

  public void testOf_one() {
    Iterable<String> iterable = MinimalIterable.of("a");
    Iterator<String> iterator = iterable.iterator();
    assertTrue(iterator.hasNext());
    assertEquals("a", iterator.next());
    assertFalse(iterator.hasNext());

    assertThrows(NoSuchElementException.class, iterator::next);
    assertThrows(IllegalStateException.class, iterable::iterator);
  }

  public void testOf_one() {
    Iterable<String> iterable = MinimalIterable.of("a");
    Iterator<String> iterator = iterable.iterator();
    assertTrue(iterator.hasNext());
    assertEquals("a", iterator.next());
    assertFalse(iterator.hasNext());

      ReferenceEntry<K, V> next = head.getNextInWriteQueue();
      return (next == head) ? null : next;
    }

    @Override
    public @Nullable ReferenceEntry<K, V> poll() {
      ReferenceEntry<K, V> next = head.getNextInWriteQueue();
      if (next == head) {
        return null;
      }

      remove(next);
      return next;
    }

    @Override

      private final StrongKeyStrongValueEntry<K, V> next;

      LinkedStrongKeyStrongValueEntry(K key, int hash, StrongKeyStrongValueEntry<K, V> next) {
        super(key, hash);
        this.next = next;
      }

      @Override
      public StrongKeyStrongValueEntry<K, V> getNext() {
        return next;
      }
    }

The main [Tutorial - User Guide](../tutorial/index.md) should be enough to give you a tour through all the main features of **FastAPI**.

In the next sections you will see other options, configurations, and additional features.

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

        protected @Nullable N computeNext() {
          for (N next = visitNext(horizon); next != null; next = visitNext(horizon)) {
            Iterator<? extends N> successors = successorFunction.successors(next).iterator();
            if (!successors.hasNext()) {
              return next;
            }
            horizon.addFirst(successors);
            ancestorStack.push(next);
          }

     * stack so that it is returned by the next call to {@link Iterator#next()}. If the element is
     * not in {@link #nextElements}, this method throws an {@link UnknownElementException}.
     *
     * <p>This method is used when testing iterators without a known ordering. We poll the target
     * iterator's next element and pass it to the reference iterator through this method so it can