Multiset<E> multiset, ObjectOutputStream stream) throws IOException {
    int entryCount = multiset.entrySet().size();
    stream.writeInt(entryCount);
    for (Multiset.Entry<E> entry : multiset.entrySet()) {
      stream.writeObject(entry.getElement());
      stream.writeInt(entry.getCount());
    }
  }

  /**
   * Populates a multiset by reading an input stream, as part of deserialization. See {@link