code: def stanza_filter(filter_, func, order=_Undefined):
      
      if order is not _Undefined:
          return filter_.context_register(func, order)
      else:
          return filter_.context_register(func)
docs: This is a deprecated alias of
      :meth:`aioxmpp.callbacks.Filter.context_register`.
  
      .. versionadded:: 0.8
  
      .. deprecated:: 0.9