Function zip_impl

include/boost/parser/detail/hl.hpp:327–330

    template<std::size_t... I, typename... Tuples>
    constexpr auto zip_impl(std::index_sequence<I...>, Tuples const &... ts)
    {
        return hl::make_tuple(hl::make_zip_elem<I>(ts...)...);
    }

    template<typename T>
    struct tuplesize;