--- a/sat_pubsub/delegation.py	Fri Aug 16 12:48:34 2019 +0200
+++ b/sat_pubsub/delegation.py	Fri Aug 16 12:53:33 2019 +0200
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #
 # Copyright (c) 2015 Jérôme Poisson
@@ -31,7 +31,7 @@
 from twisted.words.protocols.jabber import jid, error
 from twisted.words.protocols.jabber.xmlstream import toResponse
 from twisted.words.xish import domish
-from zope.interface import implements
+from zope.interface import implementer
 
 DELEGATION_NS = 'urn:xmpp:delegation:1'
 FORWARDED_NS = 'urn:xmpp:forward:0'
@@ -49,8 +49,8 @@
     pass
 
 
+@implementer(iwokkel.IDisco)
 class DelegationsHandler(XMPPHandler):
-    implements(iwokkel.IDisco)
     _service_hacked = False
 
     def __init__(self):
@@ -144,32 +144,32 @@
 
     def onAdvertise(self, message):
         """Manage the <message/> advertising delegations"""
-        delegation_elt = message.elements(DELEGATION_NS, 'delegation').next()
+        delegation_elt = next(message.elements(DELEGATION_NS, 'delegation'))
         delegated = {}
         for delegated_elt in delegation_elt.elements(DELEGATION_NS):
             try:
                 if delegated_elt.name != 'delegated':
-                    raise InvalidStanza(u'unexpected element {}'.format(delegated_elt.name))
+                    raise InvalidStanza('unexpected element {}'.format(delegated_elt.name))
                 try:
                     namespace = delegated_elt['namespace']
                 except KeyError:
-                    raise InvalidStanza(u'was expecting a "namespace" attribute in delegated element')
+                    raise InvalidStanza('was expecting a "namespace" attribute in delegated element')
                 delegated[namespace] = []
                 for attribute_elt in delegated_elt.elements(DELEGATION_NS, 'attribute'):
                     try:
                         delegated[namespace].append(attribute_elt["name"])
                     except KeyError:
-                        raise InvalidStanza(u'was expecting a "name" attribute in attribute element')
+                        raise InvalidStanza('was expecting a "name" attribute in attribute element')
             except InvalidStanza as e:
                 log.msg("Invalid stanza received ({})".format(e))
 
-        log.msg(u'delegations updated:\n{}'.format(
-            u'\n'.join([u"    - namespace {}{}".format(ns,
-            u"" if not attributes else u" with filtering on {} attribute(s)".format(
-            u", ".join(attributes))) for ns, attributes in delegated.items()])))
+        log.msg('delegations updated:\n{}'.format(
+            '\n'.join(["    - namespace {}{}".format(ns,
+            "" if not attributes else " with filtering on {} attribute(s)".format(
+            ", ".join(attributes))) for ns, attributes in list(delegated.items())])))
 
         if not pubsub.NS_PUBSUB in delegated:
-            log.msg(u"Didn't got pubsub delegation from server, can't act as a PEP service")
+            log.msg("Didn't got pubsub delegation from server, can't act as a PEP service")
 
     def onForward(self, iq):
         """Manage forwarded iq
@@ -183,14 +183,14 @@
         # TODO: do proper origin security check
         _, allowed = iq['to'].split('.', 1)
         if jid.JID(iq['from']) != jid.JID(allowed):
-            log.msg((u"SECURITY WARNING: forwarded stanza doesn't come from our server: {}"
+            log.msg(("SECURITY WARNING: forwarded stanza doesn't come from our server: {}"
                      .format(iq.toXml())).encode('utf-8'))
             raise error.StanzaError('not-allowed')
 
         try:
-            fwd_iq = (iq.elements(DELEGATION_NS, 'delegation').next()
-                      .elements(FORWARDED_NS, 'forwarded').next()
-                      .elements('jabber:client', 'iq').next())
+            delegation_elt = next(iq.elements(DELEGATION_NS, 'delegation'))
+            forwarded_elt = next(delegation_elt.elements(FORWARDED_NS, 'forwarded'))
+            fwd_iq = next(forwarded_elt.elements('jabber:client', 'iq'))
         except StopIteration:
             raise error.StanzaError('not-acceptable')