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