Function count

src/fl/stl/unordered_map.h:656–658

count() - returns 0 or 1 (unordered_map has unique keys)

    // count() - returns 0 or 1 (unordered_map has unique keys)
    fl::size count(const Key &key) const {
        return contains(key) ? 1 : 0;
    }

    // equal_range() - returns pair of iterators [it, it+1) or [end, end)
    pair<iterator, iterator> equal_range(const Key &key) {