Variadic templates not necessarily define template types. Non-types can also
be used with
    hi(variadic non-type parameters)
        variadic templates. The following function template accepts any series
of tt(int) values, forwarding these values to a class template. The class
template defines an tt(enum) value tt(result) which is returned by the
function, unless no int values were specified, in which case 0 is returned.
        verb(    template <int ...Ints>
    int forwarder()
    {
        return computer<Ints ...>::result;  // forwarding the Ints
    }

    template <>     // specialization if no ints are provided
    int forwarder<>()
    {
        return 0;
    }

    // use as:
    cout << forwarder<1, 2, 3>() << ' ' << forwarder<>() << '\n';)

The tt(sizeof) operator can be used for variadic non-type parameters as
well: tt(sizeof...(Ints)) would return 3 when used in the first function
template for tt(forwarder<1, 2, 3>()).

    Variadic non-type parameters are used to define variadic literal
operators, introduced in section ref(UDL).
