* @return the count of the element before the operation; possibly zero
   * @throws IllegalArgumentException if {@code occurrences} is negative
   */
  /*
   * TODO(cpovirk): remove and removeExactly currently accept null inputs only
   * if occurrences == 0. This satisfies both NullPointerTester and
   * CollectionRemoveTester.testRemove_nullAllowed, but it's not clear that it's

   * @return the count of the element before the operation; possibly zero
   * @throws IllegalArgumentException if {@code occurrences} is negative
   */
  /*
   * TODO(cpovirk): remove and removeExactly currently accept null inputs only
   * if occurrences == 0. This satisfies both NullPointerTester and
   * CollectionRemoveTester.testRemove_nullAllowed, but it's not clear that it's

     * @param occurrences the number of occurrences of {@code element} to remove
     * @return {@code true} if the removal was possible (including if {@code occurrences} is zero)
     */
    boolean removeExactly(@Nullable Object element, int occurrences) {
      if (occurrences == 0) {
        return true;
      }
      checkArgument(occurrences > 0, "Invalid occurrences: %s", occurrences);

      while (true) {

    assertThrows(IllegalArgumentException.class, () -> cms.removeExactly("a", -2));

    assertTrue(cms.removeExactly("a", 0));
    assertEquals(2, cms.count("a"));
    assertTrue(cms.removeExactly("c", 0));
    assertEquals(0, cms.count("c"));

    assertFalse(cms.removeExactly("a", 4));
    assertEquals(2, cms.count("a"));
    assertTrue(cms.removeExactly("a", 2));
    assertEquals(0, cms.count("a"));