code: function(view){
      var prefix = Marionette.getOption(this, "itemViewEventPrefix");
  
      // Forward all child item view events through the parent,
      // prepending "itemview:" to the event name
      this.listenTo(view, "all", function(){
        var args = slice(arguments);
        args[0] = prefix + ":" + args[0];
        args.splice(1, 0, view);
  
        Marionette.triggerMethod.apply(this, args);
      }, this);
    }
docs: Set up the child view event forwarding. Uses an "itemview:" prefix in front of all forwarded events.