Variadic version of std::is_convertible?

Question

Is it possible to write a variadic version of std::is_convertible? For example are_convertible<T1, T2, T3, T4> would return is_convertible<T1, T3> && is_convertible<T2, T4>. I've been thinking about this for a few hours but couldn't come up with anything reasonable.

To clarify I want to use it somewhat like this:

template <class ...Args1>
struct thing
{
  template <class ...Args2>
  enable_if_t<are_convertible<Args2..., Args1...>::value>
  foo(Args2 &&...args){}
}