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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 _lemmatise_roman_numerals(self, form, pos=False, get_lemma_object=False):
 """ Lemmatise un mot f si c'est un nombre romain :param form: Mot à lemmatiser :param pos: Récupère la POS :param get_lemma_object: Retrieve Lemma object instead of string representation of lemma """

        if estRomain(form):
            _lemma = Lemme(
                cle=form, graphie_accentuee=form, graphie=form, parent=self, origin=0, pos="a",
                modele=self.modele("inv")
            )
            yield Lemmatiseur.format_result(
                form=form,
                lemma=_lemma,
                with_pos=pos,
                raw_obj=get_lemma_object
            )

        if form.upper() != form:
            yield from self._lemmatise_roman_numerals(form.upper(), pos=pos, get_lemma_object=get_lemma_object)