code: function(map, attr, val) {
  	var serializer = attr === "*" ? false : getPropDefineBehavior("serialize", attr, map.define);
  	if (serializer === undefined) {
  		return oldSingleSerialize.call(map, attr, val);
  	} else if (serializer !== false) {
  		return typeof serializer === "function" ? serializer.call(map, val, attr) : oldSingleSerialize.call(map, attr, val);
  	}
  }
docs: If the map has a define serializer for the given attr, run it.