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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 user_is_blacklisted(self, user):
        '''
        Takes a username as a string and returns a boolean. True indicates that
        the provided user has been blacklisted
        '''
        return not salt.utils.stringutils.check_whitelist_blacklist(user, blacklist=self.blacklist.get('users', []))