On http://docs.python.org/3.0/tutorial/datastructures.html#sets there is
the following section in the section on sets

>>> basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}
>>> print(basket)
{'orange', 'bananna', 'pear', 'apple'}
>>> fruit = ['apple', 'orange', 'apple', 'pear', 'orange', 'banana']
>>> fruit = set(basket)               # create a set without duplicates
>>> fruit
{'orange', 'pear', 'apple', 'banana'}


The third command should be an assignment to basket rather than fruit.