code: function (attributes, options) {
      var AttrCollection = Backgrid.Extension.AdvancedFilter.AttributeFilterCollection;
      if (attributes.attributeFilters !== undefined && !(attributes.attributeFilters instanceof AttrCollection)) {
        attributes.attributeFilters = new AttrCollection(attributes.attributeFilters);
      }
      return Backbone.Model.prototype.set.call(this, attributes, options);
    }
docs: Set override
  Makes sure the attributeFilters are set as a collection.
  
  @method set
  @param {Object} attributes
  @param {Object} options
  @return {*}