Code example #1 in creating custom stanza objects using the Task example.

stanza_objects_example_1.py

import sleekxmpp
from sleekxmpp.xmlstream.stanzabase import ElementBase, ET, JID
from sleekxmpp.stanza.iq import Iq

class Param(ElementBase):
    namespace = 'example:task'
    name = 'param'
    plugin_attrib = 'param'
    interfaces = set(('name', 'value'))
    sub_interfaces = interfaces

class Task(ElementBase):
    namespace = 'example:task'
    name = 'task'
    plugin_attrib = 'task'
    interfaces = set(('id', 'command', 'cleanup', 'params'))
    sub_interfaces = set(('command', 'cleanup'))
    subitem = (Param,)