code: function (name) {
      name = name || BASE_OVERLAY;
      if (!this.instances[name]) {
        this.instances[name] = DevFixturesOverlay.create({name: name});
      }
      return this.instances[name];
    }
docs: Get the singleton instance for the given overlay name
  
  @method for
  @param {string} name
  @return {DevFixturesOverlay}