code: def claim_pep_node(self, node_namespace, *,
                         register_feature=True, notify=False):
          
          if node_namespace in self._pep_node_claims:
              raise RuntimeError(
                  "claiming already claimed node"
              )
          registered_node = RegisteredPEPNode(
              self,
              node_namespace,
              register_feature=register_feature,
              notify=notify,
          )
  
          finalizer = weakref.finalize(
              registered_node,
              weakref.WeakMethod(registered_node._unregister)
          )
          # we cannot guarantee that disco is not cleared up already,
          # so we do not unclaim the feature on exit
          finalizer.atexit = False
  
          self._pep_node_claims[node_namespace] = registered_node
  
          return registered_node
docs: Claim node `node_namespace`.
  
          :param node_namespace: the pubsub node whose events shall be
              handled.
          :param register_feature: Whether to publish the `node_namespace`
              as feature.
          :param notify: Whether to register the ``+notify`` feature to
              receive notification without explicit subscription.
          :raises RuntimeError: if a handler for `node_namespace` is already
              set.
          :returns: a :class:`~aioxmpp.pep.service.RegisteredPEPNode` instance
              representing the claim.
  
          .. seealso::
  
              :class:`aioxmpp.pep.register_pep_node`
                a descriptor which can be used with
                :class:`~aioxmpp.service.Service` subclasses to claim a PEP node
                automatically.
  
          This registers `node_namespace` as feature for service discovery
          unless ``register_feature=False`` is passed.
  
          .. note::
  
              For `notify` to work, it is required that
              :class:`aioxmpp.EntityCapsService` is loaded and that presence is
              re-sent soon after
              :meth:`~aioxmpp.EntityCapsService.on_ver_changed` fires. See the
              documentation of the class and the signal for details.