[boost] [intrusive]: determine the hook type of intrusive::list<>?

I'd like to determine the hook type of an intrusive container (intrusive::list): template< typename List > void do_link( List & lst) { static_assert(std::is_same< typename List::???, my_hook_type >::value); lst.push_back( * this); } In the documentation I didn't found a hint. Oliver