static constexpr decltype(auto) apply(Xs&& xs) {
using Raw = typename detail::std::remove_reference<Xs>::type;
constexpr auto N = ::std::tuple_size<Raw>::value;
return tail_helper(
detail::std::forward<Xs>(xs),
detail::std::make_index_sequence<N - 1>{}
);
}
static constexpr auto apply(Xs&& xs) {
constexpr std::size_t N = decltype(hana::length(xs))::value;
return tail_helper(static_cast<Xs&&>(xs),
std::make_index_sequence<N>{});
}
