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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 lemma(self):
 """ Lazy-loads the lemma for this word :getter: Returns the plain string value of the word lemma :type: str """

        if self._lemma is None:
            lemmata = self._element.xpath('lemma/text()')
            if len(lemmata) > 0:
                self._lemma = lemmata[0]
        return self._lemma