Update demo animated sprite.

demo_animated_sprite.py

@@ -36,7 +36,8 @@ def test():
             offset = SIZE * index
             display.draw_sprite(mv_cat[offset: offset + SIZE], x, y,
                                 SPRITE_WIDTH, SPRITE_HEIGHT)
-            index = (index + 1) % 8  # Set current index
+            index += 1  # Increment sprite index
+            index &= 7  # Wrap sprite index on end sprite
 
             # Attempt to set framerate to 30 FPS
             timer_dif = 33333 - ticks_diff(ticks_us(), timer)