How to use the xandikos.davcommon function in xandikos

elif tag.tag == ('{%s}expand' % NAMESPACE):
            # TODO(jelmer): https://github.com/jelmer/xandikos/issues/102
            raise NotImplementedError('expand is not yet implemented')
        elif tag.tag == ('{%s}limit-recurrence-set' % NAMESPACE):
            # TODO(jelmer): https://github.com/jelmer/xandikos/issues/103
            raise NotImplementedError(
                'limit-recurrence-set is not yet implemented')
        elif tag.tag == ('{%s}limit-freebusy-set' % NAMESPACE):
            # TODO(jelmer): https://github.com/jelmer/xandikos/issues/104
            raise NotImplementedError(
                'limit-freebusy-set is not yet implemented')
        else:
            raise AssertionError('invalid element %r' % tag)


class CalendarDataProperty(davcommon.SubbedProperty):
    """calendar-data property

    See https://tools.ietf.org/html/rfc4791, section 5.2.4

    Note that this is not technically a DAV property, and
    it is thus not registered in the regular webdav server.
    """

    name = '{%s}calendar-data' % NAMESPACE

    def supported_on(self, resource):
        return (resource.get_content_type() == 'text/calendar')

    async def get_value_ext(self, base_href, resource, el, environ, requested):
        if len(requested) == 0:
            serialized_cal = b''.join(await resource.get_body())

See https://tools.ietf.org/html/rfc6352, section 7.1.1
    """

    name = '{%s}addressbook-home-set' % NAMESPACE
    resource_type = '{DAV:}principal'
    in_allprops = False
    live = True

    async def get_value(self, base_href, resource, el, environ):
        for href in resource.get_addressbook_home_set():
            href = webdav.ensure_trailing_slash(href)
            el.append(webdav.create_href(href, base_href))


class AddressDataProperty(davcommon.SubbedProperty):
    """address-data property

    See https://tools.ietf.org/html/rfc6352, section 10.4

    Note that this is not technically a DAV property, and
    it is thus not registered in the regular webdav server.
    """

    name = '{%s}address-data' % NAMESPACE

    def supported_on(self, resource):
        return (resource.get_content_type() == 'text/vcard')

    async def get_value_ext(self, href, resource, el, environ, requested):
        # TODO(jelmer): Support subproperties
        # TODO(jelmer): Don't hardcode encoding

"""Provides calendar-description property.

    https://tools.ietf.org/html/rfc6352, section 6.2.1
    """

    name = '{%s}addressbook-description' % NAMESPACE
    resource_type = ADDRESSBOOK_RESOURCE_TYPE

    async def get_value(self, href, resource, el, environ):
        el.text = resource.get_addressbook_description()

    def set_value(self, href, resource, el):
        resource.set_addressbook_description(el.text)


class AddressbookMultiGetReporter(davcommon.MultiGetReporter):

    name = '{%s}addressbook-multiget' % NAMESPACE
    resource_type = ADDRESSBOOK_RESOURCE_TYPE
    data_property = AddressDataProperty()


class Addressbook(webdav.Collection):

    resource_types = (
        webdav.Collection.resource_types + [ADDRESSBOOK_RESOURCE_TYPE])

    def get_addressbook_description(self):
        raise NotImplementedError(self.get_addressbook_description)

    def set_addressbook_description(self, description):
        raise NotImplementedError(self.set_addressbook_description)

class CalendarOrderProperty(webdav.Property):
    """Provides calendar-order property.
    """

    name = '{http://apple.com/ns/ical/}calendar-order'
    resource_type = CALENDAR_RESOURCE_TYPE

    async def get_value(self, base_href, resource, el, environ):
        el.text = resource.get_calendar_order()

    async def set_value(self, href, resource, el):
        resource.set_calendar_order(el.text)


class CalendarMultiGetReporter(davcommon.MultiGetReporter):

    name = '{%s}calendar-multiget' % NAMESPACE
    resource_type = (CALENDAR_RESOURCE_TYPE, SCHEDULE_INBOX_RESOURCE_TYPE)
    data_property = CalendarDataProperty()


def parse_prop_filter(el, cls):
    name = el.get('name')

    # From https://tools.ietf.org/html/rfc4791, 9.7.2:
    # A CALDAV:comp-filter is said to match if:

    prop_filter = cls(name=name)

    for subel in el:
        if subel.tag == '{urn:ietf:params:xml:ns:caldav}is-not-defined':