alien.py

@@ -25,7 +25,6 @@ class Alien(Sprite):
                 return True
             elif self.rect.left <= 0:
                 return True
-
             def update(self):
                 """向左或向右移动外星人"""
                 self.x += (self.ai_settings.alien_speed_factor * self.ai_settings.fleet_direction)