Crow：Middlewares 庖丁解牛3 pop_back

紧随着产生序列

Crow：Middlewares 庖丁解牛2 产生序列-CSDN博客

的代码是pop_back:

template
struct pop_back_helper;

template
struct pop_back_helper, Tuple>
{
    template class U>
    using rebind = U::type...>;
};

template
struct pop_back
{
    template class U>
    using rebind = typename pop_back_helper::type, std::tuple>::template rebind;
};

template<>
struct pop_back<>
{
    template class U>
    u