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"));

              deltas[keyIndex] -= min(delta, oldValue);
              break;
            }
          case REMOVE_EXACTLY:
            {
              int delta = random.nextInt(5); // [0, 4]
              if (multiset.removeExactly(key, delta)) {
                deltas[keyIndex] -= delta;
              }
              break;
            }
        }
      }

   * @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