code: def __error(self,stanza):
          
          try:
              self.error(stanza.get_error())
          except ProtocolError:
              from ..error import StanzaErrorNode
              self.error(StanzaErrorNode("undefined-condition"))
docs: Handle disco error response.
  
          :Parameters:
              - `stanza`: the stanza received.
          :Types:
              - `stanza`: `pyxmpp.stanza.Stanza`