def sprite_from_sprite(spritegroup, sprite, time):
    """Takes sprites returned from a sprite and adds it to a group.
    
    sprite is first updated, and if it returns something (i.e. a
    sprite) it is added to spritegroup.
    
    """
    if sprite.alive():
        newsprite = sprite.update(time)
        if newsprite is not None:
            spritegroup.add(newsprite)
