swap

template<class Key, class Pred, class A>
    void swap(
        const multiset <Key, Pred, A>& lhs,
        const multiset <Key, Pred, A>& rhs);
template<class Key, class Pred, class A>
    void swap(
        const set <Key, Pred, A>& lhs,
        const set <Key, Pred, A>& rhs);

The template function executes lhs.swap(rhs).