xep_0077_7.py

    def __handleRegistration(self, iq):
        if iq['type'] == 'get':
            # Registration form requested
            userData = self.backend[iq['from'].bare]
            self.sendRegistrationForm(iq, userData)
        elif iq['type'] == 'set':
            if iq['register']['remove']:
                # Remove an account
                self.backend.unregister(iq['from'].bare)
                self.xmpp.event('unregistered_user', iq)
                iq.reply().send()
                return

            for field in self.form_fields:
                if not iq['register'][field]:
                    # Incomplete Registration
                    self._sendError(iq, '406', 'modify', 'not-acceptable'
                                    "Please fill in all fields.")
                    return

    ...

    def _sendError(self, iq, code, error_type, name, text=''):
        iq.reply().setPayload(iq['register'].xml)
        iq.error()
        iq['error']['code'] = code
        iq['error']['type'] = error_type
        iq['error']['condition'] = name
        iq['error']['text'] = text
        iq.send()