ai_settingsscreenand shipso we need to update the call to update_bullets(in alien_invasion pyalien_ invasion py start the main loop for the game while truegf check_events(ai_settingsscreenshipbulletsship update(gf update_bullets(ai_settingsscreenshipaliensbulletsgf update_aliens(ai_settingsaliensgf update_screen(ai_settingsscreenshipaliensbulletsnow new fleet appears as soon as you destroy the current fleet speeding up the bullets if you've tried firing at the aliens in the game' current stateyou may have noticed that the bullets have slowed down bit this is because pygame is now doing more work on each pass through the loop we can increase the speed of the bullets by adjusting the value of bullet_speed_factor in settings py if we increase this value (to for example)the bullets should travel up the screen at reasonable speed againsettings py bullet settings self bullet_speed_factor self bullet_width --snip-the best value for this setting depends on the speed of your systemso find value that works for you refactoring update_bullets(let' refactor update_bullets(so it' not doing so many different tasks we'll move the code for dealing with bullet-alien collisions to separate functiongame_ functions py def update_bullets(ai_settingsscreenshipaliensbullets)--snip-get rid of bullets that have disappeared for bullet in bullets copy()if bullet rect bottom < bullets remove(bulletcheck_bullet_alien_collisions(ai_settingsscreenshipaliensbulletsdef check_bullet_alien_collisions(ai_settingsscreenshipaliensbullets)"""respond to bullet-alien collisions ""remove any bullets and aliens that have collided collisions pygame sprite groupcollide(bulletsalienstruetruealiens