code: function tasksComplete (ui) {
  
      return function (err) {
  
          /**
           * Log any error according to BrowserSync's Logging level
           */
          if (err) {
              ui.logger.setOnce("useLevelPrefixes", true).error(err.message || err);
          }
  
          /**
           * Running event
           */
          ui.events.emit("ui:running", {instance: ui, options: ui.options});
  
          /**
           * Finally call the user-provided callback
           */
          ui.cb(null, ui);
      };
  }
docs: All async tasks complete at this point
  @param ui