The error in your problem states the list is not callable. This happens because you are trying to access/use a python list but using parenthesis for it. Parenthesis are applied to call a function and because a list is not a function, you get this error. To access or use a python list, you have to use square brackets. Try this:
print worldlists[len(words)]
To know more about this you can have a look at the following video:-