assertFalse(map.containsKey(key));

    assertEquals(value, map.addAndGet(key, value));
    assertEquals(value, map.get(key));

    assertEquals(0L, map.addAndGet(key, -1 * value));
    assertEquals(0L, map.get(key));
    assertTrue(map.containsKey(key));

    assertEquals(value, map.addAndGet(key, value));
    assertEquals(value, map.get(key));
  }

  public void testGetAndAdd() {

   */
  @CanIgnoreReturnValue
  public long incrementAndGet(K key) {
    return addAndGet(key, 1);
  }

  /**
   * Decrements by one the value currently associated with {@code key}, and returns the new value.
   */
  @CanIgnoreReturnValue
  public long decrementAndGet(K key) {
    return addAndGet(key, -1);
  }

  /**

   */
  @CanIgnoreReturnValue
  public long incrementAndGet(K key) {
    return addAndGet(key, 1);
  }

  /**
   * Decrements by one the value currently associated with {@code key}, and returns the new value.
   */
  @CanIgnoreReturnValue
  public long decrementAndGet(K key) {
    return addAndGet(key, -1);
  }

  /**

        assertBitEquals(x + y, a.get());
      }
    }
  }

  /** addAndGet adds given value to current, and returns current value */
  public void testAddAndGet() {
    for (double x : VALUES) {
      for (double y : VALUES) {
        AtomicDouble a = new AtomicDouble(x);
        double z = a.addAndGet(y);
        assertBitEquals(x + y, z);
        assertBitEquals(x + y, a.get());
      }
    }

        }
      }
    }
  }

  /** addAndGet adds given value to current, and returns current value */
  public void testAddAndGet() {
    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
    for (int i : new int[] {0, SIZE - 1}) {
      for (double x : VALUES) {
        for (double y : VALUES) {
          aa.set(i, x);
          double z = aa.addAndGet(i, y);
          assertBitEquals(x + y, z);

       */
      int frequency = requireNonNull(currentEntry).getValue().get();
      if (frequency <= 0) {
        throw new ConcurrentModificationException();
      }
      if (currentEntry.getValue().addAndGet(-1) == 0) {
        entryIterator.remove();
      }
      size--;
      canRemove = false;
    }
  }

  @Override
  public int count(@CheckForNull Object element) {

   *
   * @param i the index
   * @param delta the value to add
   * @return the updated value
   */
  @CanIgnoreReturnValue
  public double addAndGet(int i, double delta) {
    return accumulateAndGet(i, delta, Double::sum);
  }

  /**
   * Atomically updates the element at index {@code i} with the results of applying the given