code: def search_users(self, user_name):
          
          action_path = 'users'
          if user_name:
              action_path += '?search={}'.format(user_name)
  
          res = self._make_ocs_request(
              'GET',
              self.OCS_SERVICE_CLOUD,
              action_path
          )
  
          if res.status_code == 200:
              tree = ET.fromstring(res.content)
              users = [x.text for x in tree.findall('data/users/element')]
  
              return users
  
          raise HTTPResponseError(res)
docs: Searches for users via provisioning API.
          If you get back an error 999, then the provisioning API is not enabled.
  
          :param user_name:  name of user to be searched for
          :returns: list of usernames that contain user_name as substring
          :raises: HTTPResponseError in case an HTTP error status was returned