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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def assert_subset(self, subset, superset, failure_message='Expected collection "{}" to be a subset of "{}'):
 """ Asserts that a superset contains all elements of a subset """

        assertion = lambda: set(subset).issubset(set(superset))
        failure_message = unicode(failure_message).format(superset, subset)
        self.webdriver_assert(assertion, failure_message)