#ifndef __GBLIBCPP_UTILITY__
#define __GBLIBCPP_UTILITY__

namespace std {

namespace __helpers {
template <typename T>
struct __utility_remove_reference { using type = T; };
template <typename T>
struct __utility_remove_reference<T&> { using type = T; };
template <typename T>
struct __utility_remove_reference<T&&> { using type = T; };
};

template <typename T>
constexpr typename __helpers::__utility_remove_reference<T>::type&&
move(T&& val) noexcept
{
    return static_cast<
        typename __helpers::__utility_remove_reference<T>::type&&
        >(val);
}

template <typename T>
constexpr T&& forward(
    typename __helpers::__utility_remove_reference<T>::type& val) noexcept
{
    return static_cast<T&&>(val);
}
template <typename T>
constexpr T&& forward(
    typename __helpers::__utility_remove_reference<T>::type&& val) noexcept
{
    return static_cast<T&&>(val);
}

template <typename T, typename U = T>
constexpr T exchange(T& dst, U&& val)
{
    T tmp = move(dst);
    dst = forward<U>(val);
    return tmp;
}

} // namespace std

#endif