|       | The Rectangle class - header file. | Lecture 3 - slide 6 : 36 Program 1 | 
#include "point.h"
class Rectangle{
private:
  Point upper_left, lower_right;
public:
  Rectangle();
  Rectangle(Point p1, Point p2);
  Rectangle(double x1, double y1, double x2, double y2);
 
  // other methods
};