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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 _parse_reference(self, el):
 """Return reference ID from href or text content."""

        if '#' in el.get('href', ''):
            return [el.get('href').split('#', 1)[1]]
        elif 'rid' in el.attrib:
            return [el.attrib['rid']]
        elif 'idref' in el.attrib:
            return [el.attrib['idref']]
        else:
            return [''.join(el.itertext()).strip()]