anchor.diff:                        (return i)))))
            (s (if thopter
                   (format
  -                 nil "wave: ~a, health: ~a, firepower: ~a, ammo: ~a, missiles: ~a, fps: ~,2f"
  +                 nil "wave: ~a, health: ~a, firepower: ~a, ammo: ~a, missiles: ~a, speed-time: ~a, fps: ~,2f"
                    (level (game-wave screen))
                    (health thopter)
                    (ceiling (ammo thopter)
                             (ammo-deplete-rate thopter))
                    (ammo thopter)
                    (missiles thopter)
  +                 (speed-boost thopter)
                    (sdl:average-fps))
                   (if anyone-alive
                       (format
  
positive.code: 
  (defmethod collide ((thopter thopter) event)
    (with-slots (parent offset depth veloc health ammo ammo-refill-rate 
                        missiles) thopter
      (typecase (event-hit event)
        (enemy-bullet  (decf health))
        (enemy-missile (decf health))
  
negative.code: (defmethod alarm ((thopter thopter) event)
    (shoot thopter event)
    (setf (timer thopter) 4))
  
  (defmethod toggle-boost ((thopter thopter) event)
    (if (boost-on thopter)
        (progn (setf (boost-on thopter) nil) (change-veloc thopter event))
        (setf (boost-on thopter) t)))
  
  (defmethod initialize-instance :after ((shooter shooter) &key)
    (setf (ammo shooter) (* (ammo shooter) (ammo-deplete-rate shooter))))
  