code: function (callback, context) {
              SjlMap.prototype.forEach.call(this.sort(), function (value, key, map) {
                  callback.call(context, this.wrapItems ? value.value : value, key, map);
              }, this);
              return this;
          }
docs: Allows you to loop through priority items in priority list.
  Same function signature as Array.prorotype.forEach.
  @param callback {Function} - Same signature as SjlMap.prorotype.forEach; I.e., {Function<value, key, obj>}.
  @param context {undefined|*}
  @method sjl.stdlib.PriorityList#forEach
  @overrides sjl.stdlib.SjlMap#forEach
  @returns {sjl.stdlib.PriorityList}