code: def run(self):
          
          global world
          self.__is_running = True
          while(self.__is_running):
              #Our game loop
  
              #Catch our events
              self.__handle_events()
  
  	        #Update our clock
              self.__clock.tick(self.preferred_fps)
              elapsed_milliseconds = self.__clock.get_time()
      	    if 2 in self.event_flags:
                  self.elapsed_milliseconds = 0
  
              #Print the fps that the game is running at.
      	    if self.print_frames:
                  self.fpsTimer += elapsed_milliseconds
                  if self.fpsTimer > self.print_fps_frequency:
                      print "FPS: ", self.__clock.get_fps()
                      self.fpsTimer = 0.0
  
              #Update all of our objects
      	    if not 0 in self.event_flags:
          	   world.update(elapsed_milliseconds)
  
              #Draw all of our objects
      	    if not 1 in self.event_flags:
          	   world.draw(elapsed_milliseconds)
  
              #Make our world visible
              pygame.display.flip()
docs: Start the game loop