new_contents: class Canvas:
  
      def __init__(self, width, height, background_color="#FFFFFF"):
          self._width = int(width)
          self._height = int(height)
  
          self.background_color = background_color
  
          self.graphics = []
  
  
      def __repr__(self):
          return "<%i × %i canvas object with %i graphics>" % (
           self._width,
           self._height,
           len(self.graphics)
          )
  
  
      def width(self):
          return _width
  
  
      def height(self):
          return _height
  
subject: Create basic Canvas object