How to use the granary.atom.Defaulter function in granary

def activity_to_atom(activity, xml_base=None, reader=True):
  """Converts a single ActivityStreams 1 activity to an Atom entry.

  Kwargs are passed through to :func:`activities_to_atom`.

  Args:
    xml_base: the base URL, if any. Used in the top-level xml:base attribute.
    reader: boolean, whether the output will be rendered in a feed reader.
      Currently just includes location if True, not otherwise.

  Returns:
    unicode string with Atom XML
  """
  _prepare_activity(activity, reader=reader)
  return jinja_env.get_template(ENTRY_TEMPLATE).render(
    activity=Defaulter(activity),
    mimetypes=mimetypes,
    VERBS_WITH_OBJECT=source.VERBS_WITH_OBJECT,
    xml_base=xml_base,
  )

def __hash__(self):
    return super(Defaulter, self).__hash__() if self else None.__hash__()

request_url = host_url

  _prepare_actor(actor)
  for a in activities:
    _prepare_activity(a, reader=reader)

  updated = (util.get_first(activities[0], 'object', default={}).get('published', '')
             if activities else '')

  if actor is None:
    actor = {}

  return jinja_env.get_template(FEED_TEMPLATE).render(
    actor=Defaulter(actor),
    host_url=host_url,
    items=[Defaulter(a) for a in activities],
    mimetypes=mimetypes,
    rels=rels or {},
    request_url=request_url,
    title=title or 'User feed for ' + source.Source.actor_name(actor),
    updated=updated,
    VERBS_WITH_OBJECT=source.VERBS_WITH_OBJECT,
    xml_base=xml_base,
  )

Returns:
    unicode string with Atom XML
  """
  # Strip query params from URLs so that we don't include access tokens, etc
  host_url = (_remove_query_params(host_url) if host_url
              else 'https://github.com/snarfed/granary')
  if request_url is None:
    request_url = host_url

  for a in activities:
    _prepare_activity(a, reader=reader)

  if actor is None:
    actor = {}
  return jinja_env.get_template(FEED_TEMPLATE).render(
    items=[Defaulter(**a) for a in activities],
    host_url=host_url,
    request_url=request_url,
    xml_base=xml_base,
    title=title or 'User feed for ' + source.Source.actor_name(actor),
    updated=activities[0]['object'].get('published', '') if activities else '',
    actor=Defaulter(**actor),
    rels=rels or {},
    VERBS_WITH_OBJECT=source.VERBS_WITH_OBJECT,
  )

def activity_to_atom(activity, xml_base=None, reader=True):
  """Converts a single ActivityStreams 1 activity to an Atom entry.

  Kwargs are passed through to :func:`activities_to_atom`.

  Args:
    xml_base: the base URL, if any. Used in the top-level xml:base attribute.
    reader: boolean, whether the output will be rendered in a feed reader.
      Currently just includes location if True, not otherwise.

  Returns:
    unicode string with Atom XML
  """
  _prepare_activity(activity, reader=reader)
  return jinja_env.get_template(ENTRY_TEMPLATE).render(
    activity=Defaulter(**activity),
    xml_base=xml_base,
    VERBS_WITH_OBJECT=source.VERBS_WITH_OBJECT,
  )

def __hash__(self):
    return super(Defaulter, self).__hash__() if self else None.__hash__()

def __init__(self, **kwargs):
    super(Defaulter, self).__init__(Defaulter, **{
      k: (Defaulter(**v) if isinstance(v, dict) else v)
      for k, v in kwargs.items()})

def __defaulter(cls, obj):
    if isinstance(obj, dict):
      return Defaulter(obj)
    elif isinstance(obj, (tuple, list, set)):
      return obj.__class__(cls.__defaulter(elem) for elem in obj)
    else:
      return obj

else 'https://github.com/snarfed/granary')
  if request_url is None:
    request_url = host_url

  _prepare_actor(actor)
  for a in activities:
    _prepare_activity(a, reader=reader)

  updated = (util.get_first(activities[0], 'object', default={}).get('published', '')
             if activities else '')

  if actor is None:
    actor = {}

  return jinja_env.get_template(FEED_TEMPLATE).render(
    actor=Defaulter(actor),
    host_url=host_url,
    items=[Defaulter(a) for a in activities],
    mimetypes=mimetypes,
    rels=rels or {},
    request_url=request_url,
    title=title or 'User feed for ' + source.Source.actor_name(actor),
    updated=updated,
    VERBS_WITH_OBJECT=source.VERBS_WITH_OBJECT,
    xml_base=xml_base,
  )