def METHOD_NAME(self, delta_time):
    # Start update timer
    start_time = timeit.default_timer()
    self.coin_list.update()
    for sprite in self.coin_list:
        if sprite.position[0] < 0:
            sprite.change_x *= -1
        elif sprite.position[0] > SCREEN_WIDTH:
            sprite.change_x *= -1
        if sprite.position[1] < 0:
            sprite.change_y *= -1
        elif sprite.position[1] > SCREEN_HEIGHT:
            sprite.change_y *= -1
    # Save the time it took to do this.
    self.processing_time = timeit.default_timer() - start_time
    # Total time program has been running
    total_program_time = int(timeit.default_timer() - self.program_start_time)
    # Print out stats, or add more sprites
    if total_program_time > self.last_fps_reading:
        self.last_fps_reading = total_program_time
        # It takes the program a while to "warm up", so the first
        # few seconds our readings will be off. So wait some time
        # before taking readings
        if total_program_time > 5:
            # We want the program to run for a while before taking
            # timing measurements. We don't want the time it takes
            # to add new sprites to be part of that measurement. So
            # make sure we have a clear second of nothing but
            # running the sprites, and not adding the sprites.
            if total_program_time % 2 == 1:
                # Take timings
                output = f"{total_program_time}, {len(self.coin_list)}, {self.fps.get_fps():.1f}, " \
                         f"{self.processing_time:.4f}, {self.draw_time:.4f}\n"
                self.results_file.write(output)
                print(output, end="")
                if len(self.coin_list) >= STOP_COUNT:
                    pyglet.app.exit()
                    return
                self.sprite_count_list.append(len(self.coin_list))
                self.fps_list.append(round(self.fps.get_fps(), 1))
                self.processing_time_list.append(self.processing_time)
                self.drawing_time_list.append(self.draw_time)
                # Now add the coins
                self.add_coins()