How to use the slixmpp.xmlstream.handler.Callback function in slixmpp

def plugin_init(self):
        self.xmpp.register_handler(
            Callback(
                'HTTP Request',
                StanzaPath('iq/http-req'),
                self._handle_request
            )
        )
        self.xmpp.register_handler(
            Callback(
                'HTTP Response',
                StanzaPath('iq/http-resp'),
                self._handle_response
            )
        )
        register_stanza_plugin(Iq, HTTPRequest, iterable=True)
        register_stanza_plugin(Iq, HTTPResponse, iterable=True)
        register_stanza_plugin(HTTPRequest, Headers, iterable=True)
        register_stanza_plugin(HTTPRequest, HTTPData, iterable=True)

def plugin_init(self):
        register_stanza_plugin(Iq, RPCQuery)
        register_stanza_plugin(RPCQuery, MethodCall)
        register_stanza_plugin(RPCQuery, MethodResponse)

        self.xmpp.register_handler(
            Callback('RPC Call', MatchXPath('{%s}iq/{%s}query/{%s}methodCall' % (self.xmpp.default_ns, RPCQuery.namespace, RPCQuery.namespace)),
            self._handle_method_call)
        )
        self.xmpp.register_handler(
            Callback('RPC Call', MatchXPath('{%s}iq/{%s}query/{%s}methodResponse' % (self.xmpp.default_ns, RPCQuery.namespace, RPCQuery.namespace)),
            self._handle_method_response)
        )
        self.xmpp.register_handler(
            Callback('RPC Call', MatchXPath('{%s}iq/{%s}error' % (self.xmpp.default_ns, self.xmpp.default_ns)),
            self._handle_error)
        )
        self.xmpp.add_event_handler('jabber_rpc_method_call', self._on_jabber_rpc_method_call)
        self.xmpp.add_event_handler('jabber_rpc_method_response', self._on_jabber_rpc_method_response)
        self.xmpp.add_event_handler('jabber_rpc_method_fault', self._on_jabber_rpc_method_fault)
        self.xmpp.add_event_handler('jabber_rpc_error', self._on_jabber_rpc_error)
        self.xmpp.add_event_handler('error', self._handle_error)
        #self.activeCalls = []

        self.xmpp['xep_0030'].add_feature('jabber:iq:rpc')
        self.xmpp['xep_0030'].add_identity('automation','rpc')

def plugin_init(self):
        self.xmpp.register_handler(Callback(
            'nyuki event',
            StanzaPath('message/{nyuki}event'),
            self._nyuki_event))

        self.xmpp.register_handler(Callback(
            'nyuki request',
            StanzaPath('message/{nyuki}request'),
            self._nyuki_request))

        register_stanza_plugin(Message, NyukiEvent)
        register_stanza_plugin(Message, NyukiRequest)
        register_stanza_plugin(Message, NyukiResponse)

def plugin_init(self):
        self._cids = {}

        register_stanza_plugin(Iq, BitsOfBinary)
        register_stanza_plugin(Message, BitsOfBinary)
        register_stanza_plugin(Presence, BitsOfBinary)

        self.xmpp.register_handler(
            Callback('Bits of Binary - Iq',
                StanzaPath('iq/bob'),
                self._handle_bob_iq))

        self.xmpp.register_handler(
            Callback('Bits of Binary - Message',
                StanzaPath('message/bob'),
                self._handle_bob))

        self.xmpp.register_handler(
            Callback('Bits of Binary - Presence',
                StanzaPath('presence/bob'),
                self._handle_bob))

        self.api.register(self._get_bob, 'get_bob', default=True)
        self.api.register(self._set_bob, 'set_bob', default=True)
        self.api.register(self._del_bob, 'del_bob', default=True)

def plugin_init(self):
        register_stanza_plugin(Iq, BlockList)
        register_stanza_plugin(Iq, Block)
        register_stanza_plugin(Iq, Unblock)

        self.xmpp.register_handler(
                Callback('Blocked Contact',
                    StanzaPath('iq@type=set/block'),
                    self._handle_blocked))

        self.xmpp.register_handler(
                Callback('Unblocked Contact',
                    StanzaPath('iq@type=set/unblock'),
                    self._handle_unblocked))

def plugin_init(self):
        register_stanza_plugin(Iq, Confirm)
        register_stanza_plugin(Message, Confirm)

        self.xmpp.register_handler(
            Callback('Confirm',
                 StanzaPath('iq@type=get/confirm'),
                 self._handle_iq_confirm))

        self.xmpp.register_handler(
            Callback('Confirm',
                 StanzaPath('message/confirm'),
                 self._handle_message_confirm))

def plugin_init(self):
        register_stanza_plugin(Message, Markable)
        register_stanza_plugin(Message, Received)
        register_stanza_plugin(Message, Displayed)
        register_stanza_plugin(Message, Acknowledged)

        self.xmpp.register_handler(
            Callback('Received Chat Marker',
                StanzaPath('message/received'),
                self._handle_received))
        self.xmpp.register_handler(
            Callback('Displayed Chat Marker',
                StanzaPath('message/displayed'),
                self._handle_displayed))
        self.xmpp.register_handler(
            Callback('Acknowledged Chat Marker',
                StanzaPath('message/acknowledged'),
                self._handle_acknowledged))

def plugin_init(self):
        register_stanza_plugin(Message, stanza.NoSave)
        register_stanza_plugin(Iq, stanza.NoSaveQuery)

        self.xmpp.register_handler(
                Callback('Google Nosave',
                    StanzaPath('iq@type=set/google_nosave'),
                    self._handle_nosave_change))

CoroutineCallback('Stream Features',
                     MatchXPath('{%s}features' % self.stream_ns),
                     self._handle_stream_features))
        def roster_push_filter(iq):
            from_ = iq['from']
            if from_ and from_ != JID('') and from_ != self.boundjid.bare:
                reply = iq.reply()
                reply['type'] = 'error'
                reply['error']['type'] = 'cancel'
                reply['error']['code'] = 503
                reply['error']['condition'] = 'service-unavailable'
                reply.send()
                return
            self.event('roster_update', iq)
        self.register_handler(
                Callback('Roster Update',
                         StanzaPath('iq@type=set/roster'),
                         roster_push_filter))

        # Setup default stream features
        self.register_plugin('feature_starttls')
        self.register_plugin('feature_bind')
        self.register_plugin('feature_session')
        self.register_plugin('feature_rosterver')
        self.register_plugin('feature_preapproval')
        self.register_plugin('feature_mechanisms')

        if sasl_mech:
            self['feature_mechanisms'].use_mech = sasl_mech

self.mech = None
        self.mech_list = set()
        self.attempted_mechs = set()

        register_stanza_plugin(StreamFeatures, stanza.Mechanisms)

        self.xmpp.register_stanza(stanza.Success)
        self.xmpp.register_stanza(stanza.Failure)
        self.xmpp.register_stanza(stanza.Auth)
        self.xmpp.register_stanza(stanza.Challenge)
        self.xmpp.register_stanza(stanza.Response)
        self.xmpp.register_stanza(stanza.Abort)

        self.xmpp.register_handler(
                Callback('SASL Success',
                         MatchXPath(stanza.Success.tag_name()),
                         self._handle_success,
                         instream=True))
        self.xmpp.register_handler(
                Callback('SASL Failure',
                         MatchXPath(stanza.Failure.tag_name()),
                         self._handle_fail,
                         instream=True))
        self.xmpp.register_handler(
                Callback('SASL Challenge',
                         MatchXPath(stanza.Challenge.tag_name()),
                         self._handle_challenge))

        self.xmpp.register_feature('mechanisms',
                self._handle_sasl_auth,
                restart=True,