template<typename U=J, typename = std::enable_if_t<std::is_same_v<U, void>>>
            graph(causal::core::dispatcher& disp) :
            _space_nodes(new causal::core::space<causal::core::typed_id<ID>, J>()),
            _space_edges(new causal::core::space<causal::core::typed_id<edge_ID>, J>()),
            branch(disp) {}

            template<typename U=J, typename = std::enable_if_t<!std::is_same_v<U, void>>>
            graph(J& driver, causal::core::dispatcher& disp) :
            _space_nodes(new causal::core::space<causal::core::typed_id<ID>, J>(driver)),
            _space_edges(new causal::core::space<causal::core::typed_id<edge_ID>, J>(driver)),
            branch(disp) {}