text: # Class definition ...
  #
  # Use docstring to lists attributes
  
   
  class Rectangle:
      """Represents a rectangle.
      attributes: width, height, corner
      """
  
  class Point:
      """A 2-D point"""
      # simple comment (not used by __doc__)
  
  print(Rectangle.__doc__) 
      # Represents a rectangle.
      #     attributes: width, height, corner - Look Here
  
  print(Point.__doc__) 
      # A 2-D point
  
  
  box = Rectangle()
  box.width = 100
  box.height = 200
  box.corner = Point() # corner - embeded object
  box.corner.x = 10
  box.corner.y = 20
  
  assert box.width == 100
  assert box.corner.x == 10