code: function(Child, Parent) {
      var hasProp = {}.hasOwnProperty;
  
      function T() {
          this.constructor = Child;
          this.constructor$ = Parent;
          for (var propertyName in Parent.prototype) {
              if (hasProp.call(Parent.prototype, propertyName) &&
                  propertyName.charAt(propertyName.length-1) !== "$"
             ) {
                  this[propertyName + "$"] = Parent.prototype[propertyName];
              }
          }
      }
      T.prototype = Parent.prototype;
      Child.prototype = new T();
      return Child.prototype;
  }
docs: Un-magical enough that using this doesn't prevent extending classes from outside using any convention