swap

template<class Key, class T, class Pred, class A>
    void swap(
        map <Key, T, Pred, A>& lhs,
        map <Key, T, Pred, A>& rhs);
template<class Key, class T, class Pred, class A>
    void swap(
        multimap <Key, T, Pred, A>& lhs,
        multimap <Key, T, Pred, A>& rhs);