public class Rectangle extends Shape {
  private double length;
  private double width;
  //private double area;

  public Rectangle(double length, double  width) {
    super(length * width);
    this.length = length;
    this.width = width;
  }

  public double area() {
    return area;
  }

  public String toString() {
    return "rectangle of area " + area();
  }
}