I needed to add the following two lines to the top of your script in order for it to run properly:
Code:
import random
import viztask
Also, make sure you don't have any other file in the same directory as your script that is named
random.py. If you do, this might conflict with the built-in random module.
Also, can you explain in more detail what behavior you are expecting? Should the box disappear after it looms, or should it go back to its original position?