var Shapes = (function () {
    var Shape = (function () {
      }

    Shape.prototype.toString = function () {};

    return Shape;
    }());

    var Circle = (function () {
      function Circle () {
      }

        Circle.extends(Shape);

        Circle.prototype.toString = function() {
          Shape.prototype.toString.call(this);
      // ....
        };

        return Circle;
    }());

    var Rectangle = (function () {
      function Rectangle () {
      }

        Rectangle.extends(Shape);

        Rectangle.prototype.toString = function() {
          Shape.prototype.toString.call(this);
          // ...
        };

        return Rectangle;
    }());

    return {
      Shape: Shape,
      Circle: Circle,
      Rectangle: Rectangle
    };

}());