.        *  Note that this function only erases the element, and that if        *  the element is itself a pointer, the pointed-to memory is not touched        *  in any way.  Managing the pointer is the user's responsibility.        */       iterator       erase(const_iterator __first, const_iterator __last)       { return _M_h.erase(__first, __last); }        /**        *  Erases all elements in an %unordered_