Takes a username as a string and returns a boolean. True indicates that
        the provided user has been blacklisted

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', []))