code: function(fn) {
        var keys = Object.keys(self);
        for(var i = keys.length - 1; i >= 0; i--) {
          var key = keys[i];
          if(!UT.Collection.isReservedKey(key)) {
            fn(key, self[key]);
          }
        }
      }
docs: retrieve properties defined on this that are not reserved keywords.