How to use the nbxmpp.Error function in nbxmpp

def build_http_auth_answer(self, stanza, answer):
        if answer == 'yes':
            self._log.info('Auth request approved')
            confirm = stanza.getTag('confirm')
            reply = stanza.buildReply('result')
            if stanza.getName() == 'message':
                reply.addChild(node=confirm)
            self._con.connection.send(reply)
        elif answer == 'no':
            self._log.info('Auth request denied')
            err = nbxmpp.Error(stanza, nbxmpp.protocol.ERR_NOT_AUTHORIZED)
            self._con.connection.send(err)

def badRequest(self, stanza):
        self.connection.connection.send(nbxmpp.Error(stanza,
            nbxmpp.NS_STANZAS + ' bad-request'))

def _CommandExecuteCB(self, con, iq_obj):
        jid = helpers.get_full_jid_from_iq(iq_obj)

        cmd = iq_obj.getTag('command')
        if cmd is None: return

        node = cmd.getAttr('node')
        if node is None: return

        sessionid = cmd.getAttr('sessionid')
        if sessionid is None:
            # we start a new command session... only if we are visible for the jid
            # and command exist
            if node not in self.__commands.keys():
                self.connection.send(
                    nbxmpp.Error(iq_obj, nbxmpp.NS_STANZAS + ' item-not-found'))
                raise nbxmpp.NodeProcessed

            newcmd = self.__commands[node]
            if not newcmd.isVisibleFor(self.isSameJID(jid)):
                return

            # generate new sessionid
            sessionid = self.connection.getAnID()

            # create new instance and run it
            obj = newcmd(conn = self, jid = jid, sessionid = sessionid)
            rc = obj.execute(iq_obj)
            if rc:
                self.__sessions[(jid, sessionid, node)] = obj
            raise nbxmpp.NodeProcessed
        else:

def __send_error(self, stanza, error, jingle_error=None, text=None, type_=None):
        err_stanza = nbxmpp.Error(stanza, '%s %s' % (Namespace.STANZAS, error))
        err = err_stanza.getTag('error')
        if type_:
            err.setAttr('type', type_)
        if jingle_error:
            err.setTag(jingle_error, namespace=Namespace.JINGLE_ERRORS)
        if text:
            err.setTagData('text', text)
        self.connection.connection.send(err_stanza)
        self.__dispatch_error(jingle_error or error, text, type_)

def bad_request(self, stanza):
        self.connection.connection.send(
            nbxmpp.Error(stanza, Namespace.STANZAS + ' bad-request'))

feature.setNamespace(nbxmpp.NS_FEATURE)

        x = nbxmpp.DataForm(typ='submit')

        x.addChild(node=nbxmpp.DataField(name='FORM_TYPE',
            value='urn:xmpp:ssn'))
        x.addChild(node=nbxmpp.DataField(name='accept', value='true'))

        x.addChild(node=nbxmpp.DataField(name='logging', value=logging))

        self.status = 'responded-archiving'

        feature.addChild(node=x)

        if not logging:
            response = nbxmpp.Error(response, nbxmpp.ERR_NOT_ACCEPTABLE)

            feature = nbxmpp.Node(nbxmpp.NS_FEATURE + ' feature')

            n = nbxmpp.Node('field')
            n['var'] = 'logging'
            feature.addChild(node=n)

            response.T.error.addChild(node=feature)

        self.send(response)

def fail_bad_negotiation(self, reason, fields=None):
        """
        Send an error and cancels everything

        If fields is None, the remote party has given us a bad cryptographic
        value of some kind. Otherwise, list the fields we haven't implemented.
        """
        err = nbxmpp.Error(nbxmpp.Message(), nbxmpp.ERR_FEATURE_NOT_IMPLEMENTED)
        err.T.error.T.text.setData(reason)

        if fields:
            feature = nbxmpp.Node(nbxmpp.NS_FEATURE + ' feature')

            for field in fields:
                fn = nbxmpp.Node('field')
                fn['var'] = field
                feature.addChild(node=feature)

            err.addChild(node=feature)

        self.send(err)

        self.status = None
        self.enable_encryption = False