multiset

template<class t, class less>
struct multiset
{
 
  typedef set_iterator<t> iterator;

  multiset(const char* name);

  multiset(const char* name,
      const char* directory);

  multiset(const wchar_t* name);

  multiset(const wchar_t* name,
      const wchar_t* directory)

  ~multiset();

  multiset<t>& operator<<(const t& element);

  t back();

  iterator begin() const;

  long long depth() const; 

  iterator end() const;

  void erase();

  long long erase(const t& key);

  bool contains(const t& element) const;

  t front();

  list<t> find(const t& key) const;

  void insert(const t& element);

  long long length() const;
};