PQueue_pop_min< typename base_class::gc >()(dest, *this);             }              void clear()             {                 base_class::clear();             }              bool empty() const             {                 return base_class::empty();             }              size_t size() const             {                 return base_class::size();             }              typename base_class::stat const& statistics() const             {                 return base_class::statistics();             }         };      