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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 _style_name(self, el):
 """Return the style name of an element."""

        if el.attributes is None:
            return None
        style_field = ('urn:oasis:names:tc:opendocument:xmlns:text:1.0',
                       'style-name')
        name = el.attributes.get(style_field, None)
        if not name:
            return None
        return self._get_style_name(name)