template<typename T>
class SortedEntitiesPointers
{
public:
    using vector = std::vector<od::not_null<T*>>;
    using iterator = typename vector::iterator;
    using const_iterator = typename vector::const_iterator;

    void add(od::not_null<T*> ptr);
    void remove(od::not_null<T*> ptr);

    iterator begin() { return _t.begin(); }
    iterator end() { return _t.begin(); }
    const_iterator begin() const { return _t.begin(); }
    const_iterator end() const { return _t.begin(); }

    const vector& data() const { return _t; }

private:
    vector _t;
};