code: function process (event, nxt) {
  
        // Publish it now...
        debug('publish event...');
        dispatcher.publisher(event.payload, function(err) {
          if (err) {
            return debug(err);
          }
          // ...and set the published event to dispatched.
          debug('set event to dispatched...');
          dispatcher.store.setEventToDispatched(event, function(err) {
            if (err) {
              debug(err);
            } else {
              debug('event set to dispatched');
            }
          });
        });
  
        nxt();
      }
docs: dipatch one event in queue and call the _next_ callback, which will call _process_ for the next undispatched event in queue.