code: def ensure(self, subsystem, name):
          
          args = {
              'subsystem': subsystem,
              'name': name,
          }
  
          self._cgroup_chk.check(args)
          return self._client.json('cgroup.ensure', args)
docs: Creates a cgroup if it doesn't exist under the specified subsystem
          and the given name
  
          :param subsystem: the cgroup subsystem (currently support 'memory', and 'cpuset')
          :param name: name of the cgroup to delete