code: function getRenderer(layer) {
           // first ensure a renderer is associated to this map
           if (typeof this.renderer === "undefined" || !this.renderer.canRender(this)) {
             this.renderer = getNewDefaultRenderer(this);
           } // return a renderer for the given layer (if any)
  
  
           if (typeof layer !== "undefined" && !this.renderer.canRender(layer)) {
             return getNewDefaultRenderer(layer);
           } // else return this renderer
  
  
           return this.renderer;
         }
docs: Return the map default renderer
  @name getRenderer
  @memberOf me.TMXTileMap
  @public
  @function
  @param {me.TMXLayer} [layer] a layer object
  @return {me.TMXRenderer} a TMX renderer