title: Swift Combine - Create publisher for CoreLocation
body: <p>I have only started learning combine, so it's still a little fuzzy to me. I would like to create a custom <code>Publisher</code>, that would use <code>CLLocationManager</code> to expose current user location. I would like it to work in such a way, that <code>locationManager</code> only starts updating location when there are some subscribers connected. And after all subscribers were removed, canceled, etc, then it should stop updating location. Is this possible to do? How can I create such a <code>publisher</code>? Also is this the right approach, or is there something wrong with it?</p>