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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 revoke_user(self, user_id):
 """ Revoke a user from the tenant This will remove pending or approved roles but will not not delete the user from Keystone. """


        uri = 'openstack/users/%s' % user_id
        try:
            resp = self.delete(uri)
        except AttributeError:
            # note: this breaks. stacktask returns a string, not json.
            return
        self.expected_success(200, resp.status)
        return rest_client.ResponseBody(resp, None)