#include <cassert>
#include <memory>
#include <utility>

int next_id() {
    static int value = 0;
    return ++value;
}

int main() {
    std::unique_ptr<int> owner;
    {
        auto local = std::make_unique<int>(42);
        owner = std::move(local);
        assert(!local);
    }
    assert(*owner == 42);
    assert(next_id() == 1);
    assert(next_id() == 2);
}