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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 del_user(self, username):
 """ Delete a user from the backend :param username: 'key' attribute of the user :type username: string """

        self._check_fix_users(username)
        try:
            del self.users[username]
        except Exception as e:
            raise UserDoesntExist(username, self.backend_name)