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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_list(self, params=None):
 """Lists all users within the tenant."""


        uri = 'openstack/users'
        if params:
            uri += '?%s' % urllib.urlencode(params)

        resp, body = self.get(uri)
        self.expected_success(200, resp.status)
        body = json.loads(body)
        return rest_client.ResponseBody(resp, body)