iterator.remove();
      assertEquals(initialSize - 1, map.size());

      // Use "entryCopy" instead of "entry" because "entry" might be invalidated after
      // iterator.remove().
      assertFalse(entrySet.contains(entryCopy));
      assertInvariants(map);
      assertThrows(IllegalStateException.class, iterator::remove);
    } else {
      iterator.next();

   *
   * <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

   */
  void add(Range<C> range);

  /**
   * Removes the specified range from this {@code RangeSet} (optional operation). After this
   * operation, if {@code range.contains(c)}, {@code this.contains(c)} will return {@code false}.
   *
   * <p>If {@code range} is empty, this is a no-op.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code remove}
   *     operation
   */

        recurse(level + 1);
      }
    }
  }

  private void compareResultsForThisListOfStimuli() {
    int removes = frequency(asList(stimuli), remove);
    if ((!features.contains(IteratorFeature.SUPPORTS_REMOVE) && removes > 1)
        || (stimuli.length >= 5 && removes > 2)) {
      // removes are the most expensive thing to test, since they often throw exceptions with stack
      // traces, so we test them a bit less aggressively

  @CollectionSize.Require(absent = ZERO)
  public void testRemoveKeyRemovesFromInverse() {
    getMap().remove(k0());
    expectMissing(e0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveKeyFromKeySetRemovesFromInverse() {
    getMap().keySet().remove(k0());
    expectMissing(e0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)

    }

    @Override
    public void remove() {
      checkRemove(canRemove);
      if (totalCount == 1) {
        entryIterator.remove();
      } else {
        /*
         * requireNonNull is safe because canRemove is set to true only after we initialize
         * currentEntry (which we never subsequently clear).
         */
        multiset.remove(requireNonNull(currentEntry).getElement());
      }

    }

    @Override
    public void remove() {
      checkRemove(canRemove);
      if (totalCount == 1) {
        entryIterator.remove();
      } else {
        /*
         * requireNonNull is safe because canRemove is set to true only after we initialize
         * currentEntry (which we never subsequently clear).
         */
        multiset.remove(requireNonNull(currentEntry).getElement());
      }

      iterator.remove();
      assertEquals(initialSize - 1, map.size());

      // Use "entryCopy" instead of "entry" because "entry" might be invalidated after
      // iterator.remove().
      assertFalse(entrySet.contains(entryCopy));
      assertInvariants(map);
      assertThrows(IllegalStateException.class, iterator::remove);
    } else {
      iterator.next();

      previous = current = next;
      next = next.next;
      nextIndex++;
      return current;
    }

    @Override
    public void remove() {
      checkForConcurrentModification();
      checkState(current != null, "no calls to next() since the last call to remove()");
      if (current != next) { // after call to next()
        previous = current.previous;
        nextIndex--;

  public void testRemoveAtIndex_unsupported() {
    assertThrows(UnsupportedOperationException.class, () -> getList().remove(0));
    expectUnchanged();
  }

  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)
  public void testRemoveAtIndex_negative() {
    assertThrows(IndexOutOfBoundsException.class, () -> getList().remove(-1));
    expectUnchanged();
  }

  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)