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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 add_user_to_group(self, user_name, group_name):
 """Adds a user to a group. :param user_name: name of user to be added :param group_name: name of group user is to be added to :returns: True if user added :raises: HTTPResponseError in case an HTTP error status was returned """


        res = self._make_ocs_request(
            'POST',
            self.OCS_SERVICE_CLOUD,
            'users/' + user_name + '/groups',
            data={'groupid': group_name}
        )

        if res.status_code == 200:
            tree = ET.fromstring(res.content)
            self._check_ocs_status(tree, [100])
            return True

        raise HTTPResponseError(res)