Function equal_range

src/fl/stl/unordered_map.h:661–669

equal_range() - returns pair of iterators [it, it+1) or [end, end)

    // equal_range() - returns pair of iterators [it, it+1) or [end, end)
    pair<iterator, iterator> equal_range(const Key &key) {
        iterator it = find(key);
        if (it == end()) {
            return {end(), end()};
        }
        iterator next = it;
        ++next;
        return {it, next};
    }

    pair<const_iterator, const_iterator> equal_range(const Key &key) const {
        const_iterator it = find(key);