set_hashtable<_Value, _Hash, _Pred, _Alloc>  _Hashtable;       _Hashtable _M_h;      public:       // typedefs:       //@{       /// Public typedefs.       typedef typename _Hashtable::key_type key_type;       typedef typename _Hashtable::value_type value_type;       typedef typename _Hashtable::hasher hasher;       typedef typename _Hashtable::key_equal key_equal;       typedef typename _Hashtable::allocator_type allocator_type;       //@}        //@{       ///  Iterator-related typedefs.       typedef typename allocator_type::pointer  pointer;       typedef typename allocator_type::const_pointer const_pointer;       typedef typename allocator_type::reference reference;       typedef typename allocator_type::const_reference const_reference;       typedef typename _Hashtable::iterator  iterator;       typedef typename _Hashtable::const_iterator const_iterator;       typedef typename _Hashtable::local_iterator local_iterator;       typedef typename _Hashtable::const_local_iterator const_local_iterator;       typedef typename _Hashtable::size_type  size_type;       typedef typename _Hashtable::difference_type difference_type;       //@}        // construct/destroy/copy       /**        *  @brief  Default constructor creates no elements.        *  @param __n  Initial number of buckets.        *  @param __hf  A hash functor.        *  @param __eql  A key equality functor.        *  @param __a  An allocator object.        */       explicit       unordered_