/*
* Copyright Ofee Oficsu 2020.
*
* Distributed under the Boost Software License, Version 1.0.
* (See license at https://www.boost.org/LICENSE_1_0.txt)
*/


template<unsigned I> struct priority_tag : priority_tag<I-1> {};
template<> struct priority_tag<0> {};

template<typename... T>
struct tag {};


template<typename, typename>
struct move_to_back { };

template<typename T, typename... Ts>
struct move_to_back<T, tag<Ts...>>
{
   using type = tag<Ts..., T>;
};

template<typename... Ts>
struct revert
{
   using type = tag<>;
};

template<typename T, typename... Ts>
struct revert<T, Ts...>
{
   using type = typename move_to_back<T, typename revert<Ts...>::type>::type;
};

template<typename... Ts>
using revert_t = typename revert<Ts...>::type;


template<template<typename...> typename Template, typename... Ts>
Template<Ts...> instantiate(priority_tag<1>, tag<Ts...>) {};

template<template<typename> typename Template, typename T>
Template<T> instantiate(priority_tag<2>, tag<T>) {};

template<template<typename…

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