ValueMediator.h Issue

[amcbride11]

Having an issue with popValues on line 215.
template<typename ...Types>
std::tuple<Types...> popValues(Handle state) {
// Initialise tuple with default values for each type of Parameters.
std::tuple<Types...> values{ ValueMediator::defaultValue()... };
impl::rpopValues(state, &values);

            return std::move(values);
        }

error: implicit instantiation of undefined template