new_contents: class Bullet:
      def __int__(self):
          self.screen = pygame.display.set_mode(SCREEN_SIZE, FULLSCREEN)
          self.x = 0
          self.y = 0
          self.r = 0
          self.rad = 0
  
      def update(self):
          self.x += self.r
          self.y += self.r
  
      def draw(self):
          pygame.draw.circle(self.screen, (255,0,0), (int(x), int(y)), 20)
  
subject: add Bullet class