assertTrue(cycle.hasNext());
    assertThrows(IllegalStateException.class, () -> cycle.remove());
  }

  public void testCycleRemoveSameElementTwice() {
    Iterator<String> cycle = Iterators.cycle("a", "b");
    cycle.next();
    cycle.remove();
    assertThrows(IllegalStateException.class, () -> cycle.remove());
  }

  public void testCycleWhenRemoveIsNotSupported() {

    assertTrue(cycle.hasNext());
    assertThrows(IllegalStateException.class, () -> cycle.remove());
  }

  public void testCycleRemoveSameElementTwice() {
    Iterator<String> cycle = Iterators.cycle("a", "b");
    cycle.next();
    cycle.remove();
    assertThrows(IllegalStateException.class, () -> cycle.remove());
  }

  public void testCycleWhenRemoveIsNotSupported() {

      }

      @Override
      public void remove() {
        iterator.remove();
      }
    };
  }

  /**
   * Returns an iterator that cycles indefinitely over the provided elements.
   *
   * <p>The returned iterator supports {@code remove()}. After {@code remove()} is called,
   * subsequent cycles omit the removed element, but {@code elements} does not change. The

    E x = items[takeIndex];
    items[takeIndex] = null;
    takeIndex = inc(takeIndex);
    --count;
    return x;
  }

  /**
   * Utility for remove and iterator.remove: Delete item at position i. Call only when occupying
   * monitor.
   */
  void removeAt(int i) {
    E[] items = this.items;
    // if removing front item, just advance
    if (i == takeIndex) {
      items[takeIndex] = null;

    }

    /**
     * Removes the specified element from this set if it is present.
     *
     * @param o
     *            object to be removed from this set, if present.
     * @return true if the set contained the specified element.
     */
    @Override
    public boolean remove(final Object o) {
        return map.remove(o) == PRESENT;
    }

    /**

     */
    public boolean contains(final E element) {
        return indexOf(element) != -1;
    }

    /**
     * Removes an element from the list.
     *
     * @param element the element
     * @return true if the element was removed, false otherwise
     */
    public boolean remove(final E element) {
        if (element == null) {
            for (Entry e = header.next; e != header; e = e.next) {

      K key = keys[entry];
      removeEntryValueHashKnown(entry, valueHash);
      return key;
    }
  }

  /** Removes the entry at the specified index with no additional data. */
  void removeEntry(int entry) {
    removeEntryKeyHashKnown(entry, Hashing.smearedHash(keys[entry]));
  }

  /** Removes the entry at the specified index, given the hash of its key and value. */

   *
   * <p>This method refines {@link Collection#remove} to further specify that it <b>may not</b>
   * throw an exception in response to {@code element} being null or of the wrong type.
   *
   * <p>To both remove the element and obtain the previous count of that element, use {@link
   * #remove(Object, int) remove}{@code (element, 1)} instead.
   *
   * @param element the element to remove one occurrence of

    }

    /**
     * Removes the mapping for a key from this map if it is present.
     *
     * @param key the key whose mapping is to be removed from the map
     * @return the previous value associated with key, or null if no mapping existed
     */
    @Override
    public Object remove(final Object key) {
        return parent.remove(key);
    }

    /**

   *
   * <p>This method refines {@link Collection#remove} to further specify that it <b>may not</b>
   * throw an exception in response to {@code element} being null or of the wrong type.
   *
   * <p>To both remove the element and obtain the previous count of that element, use {@link
   * #remove(Object, int) remove}{@code (element, 1)} instead.
   *
   * @param element the element to remove one occurrence of