Function enum_underlying

include/magic_enum/magic_enum.hpp:1261–1263

// Returns underlying value from enum value.
template <typename E>
[[nodiscard]] constexpr auto enum_underlying(E value) noexcept -> underlying_type_t<E> {
  return static_cast<underlying_type_t<E>>(value);
}

// Returns index in enum values from enum value.
// Returns optional with index.