Method lower_bound

src/fl/stl/multi_set.h:327–330

    }

    iterator lower_bound(const Key& key) {
        ValueWithId search_key(key, 0);
        return iterator(mTree.lower_bound(search_key));
    }

    const_iterator lower_bound(const Key& key) const {
        ValueWithId search_key(key, 0);