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

int main() {
    auto item = std::make_unique<int>(7);
    int* observer = item.get();
    std::vector<std::unique_ptr<int>> items;
    items.push_back(std::move(item));
    assert(!item);
    assert(items.front().get() == observer);
    assert(*observer == 7);
    *items.front() = 9;
    assert(*observer == 9);
}