player/js/utils/expressions/PropertyGroupFactory.js

var propertyGroupFactory = (function () {
  return function (interfaceFunction, parentPropertyGroup) {
    return function (val) {
      val = val === undefined ? 1 : val;
      if (val <= 0) {
        return interfaceFunction;
      } else {
        return parentPropertyGroup(val - 1);
      }
    };
  };
}());