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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 get_extended_metadata(self, item_id):
 """Get extended metadata for a media item, such as related items. Args: item_id (str):
 The item for which metadata is required. Returns: ~collections.OrderedDict: The item's extended metadata or None. See also: The Sonos `getExtendedMetadata API <http://musicpartners.sonos.com/node/128>`_ """

        response = self.soap_client.call(
            'getExtendedMetadata',
            [('id', item_id)])
        return response.get('getExtendedMetadataResult', None)