If a sprite is currently using the pen because of the down() function, the up() function will cause the sprite to stop drawing a trail. (Otherwise, it has no effect.)
The example demonstrates how to make the sprite track and stamp its image on the mouse when the space key is pressed in Python.
Code
sprite = Sprite('Tobi')
pen = Pen()
pen.clear()
while True:
if (sprite.iskeypressed("space")):
sprite.setx(sprite.mousex())
sprite.sety(sprite.mousey())
pen.stamp()