old_contents: import Vector
  try:
      import simplegui
  except ImportError:
      import SimpleGUICS2Pygame.simpleguics2pygame as simplegui
  
  img = simplegui.load_image("http://www.cs.rhul.ac.uk/courses/CS1830/asteroids/asteroid_blue.png")
  
  class Rock:
      def __init__(self, p, v):
          self.pos = Vector.Vector(p)
          self.vel = Vector.Vector(v)
          self.size = 90
  
      def update(self):
          self.pos.add(self.vel)
  
      def draw(self, canvas):
          canvas.draw_image(img, (self.size/2, self.size/2), (self.size, self.size), self.pos.getP(), (self.size, self.size))
  
      def offset(self, c):
          if c == 'l': return self.pos.x-self.size/2
          elif c == 'r': return self.pos.x+self.size/2
          elif c == 'u': return self.pos.y-self.size/2
          else: return self.pos.y+-self.size/2
  
new_contents: """
  Rock.py
  The module that implements asteroids
  """
  
  try:
      import simplegui
  except ImportError:
      import SimpleGUICS2Pygame.simpleguics2pygame as simplegui
  import Vector
  
  IMG = simplegui.load_image("http://www.cs.rhul.ac.uk/courses/CS1830/asteroids/asteroid_blue.png")
  
  class Rock:
      """
      Rock class
      """
      def __init__(self, p, v):
          self.pos = Vector.Vector(p)
          self.vel = Vector.Vector(v)
          self.size = 90
  
      def update(self):
          """
          Updates the position of the rock
          """
          self.pos.add(self.vel)
  
      def draw(self, canvas):
          """
          Draw the rock
          """
          canvas.draw_image(IMG, (self.size/2, self.size/2), (self.size, self.size), self.pos.get_pt(),\
          (self.size, self.size))
  
      def offset(self, char):
          """
          Offsets of the rock
          """
          if char == 'l':
              return self.pos.x-self.size/2
          elif char == 'r':
              return self.pos.x+self.size/2
          elif char == 'u':
              return self.pos.y-self.size/2
          else:
              return self.pos.y+-self.size/2
  
subject: Update Rock.py