// (1)
template <typename D, typename E>
EventSource<D,E> MakeEventSource();
// (2)
template <typename D>
EventSource<D,Token> MakeEventSource();
Creates a new event source node and links it to the returned EventSource
instance.
For (1), the event value type E
has to be specified explicitly.
If it’s omitted, (2) will create a token source.