[C++ Template] Make enumrate interval

[C++ Template] Make enumrate interval.h

template<size_t ...args>
struct enumrate_interval_pack  {};

template<size_t ...args>
struct enumrate_interval_impl  {
  using type = enumrate_interval_pack<args...>;
};

template<size_t l, size_t h, size_t ...args>
struct enumrate_interval   {
  using type = typename std::conditional_t<(l < h), typename enumrate_interval<l, (h - 1), h, args...>, enumrate_interval_impl<h, args...>>::type;
};

template<size_t l, size_t h, size_t ...args>
using enumrate_interval_t = typename enumrate_interval<l, h, args...>::type;