code: def events_mark_seen(self, event):
          
          last_seen = event if isinstance(event, int) else event.id
          self.client.post('{}/seen'.format(Event.api_endpoint), model=Event(self.client, last_seen))
docs: Marks event as the last event we have seen.  If event is an int, it is treated
          as an event_id, otherwise it should be an event object whose id will be used.