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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def iter_identities(self, stanza=None):
 """ Return an iterator of tuples describing the identities of the node. :param stanza: The IQ request stanza :type stanza: :class:`~aioxmpp.IQ` or :data:`None` :rtype: iterable of (:class:`str`, :class:`str`, :class:`str` or :data:`None`, :class:`str` or :data:`None`) tuples :return: :xep:`30` identities of this node `stanza` can be the :class:`aioxmpp.IQ` stanza of the request. This can be used to hide a node depending on who is asking. If the returned iterable is empty, the :class:`~.DiscoServer` returns an ``<item-not-found/>`` error. `stanza` may be :data:`None` if the identities are queried without a specific request context. In that case, implementors should assume that the result is visible to everybody. .. note:: Subclasses must allow :data:`None` for `stanza` and default it to :data:`None`. Return an iterator which yields tuples consisting of the category, the type, the language code and the name of each identity declared in this :class:`Node`. Both the language code and the name may be :data:`None`, if no names or a name without language code have been declared. """

        for (category, type_), names in self._identities.items():
            for lang, name in names.items():
                yield category, type_, lang, name
            if not names:
                yield category, type_, None, None