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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 tagged_users(self) -> List[str]: """List of all lowercased users that are tagged in the Post."""

        try:
            return [edge['node']['user']['username'].lower() for edge in self._field('edge_media_to_tagged_user',
                                                                                     'edges')]
        except KeyError:
            return []