code: function(){
      this.regionManager = new Marionette.RegionManager();
  
      this.listenTo(this.regionManager, "region:add", function(name, region){
        this[name] = region;
        this.trigger("region:add", name, region);
      });
  
      this.listenTo(this.regionManager, "region:remove", function(name, region){
        delete this[name];
        this.trigger("region:remove", name, region);
      });
    }
docs: Internal method to initialize the region manager and all regions in it