code: def get_extended_metadata_text(self, item_id, metadata_type):
          
          response = self.soap_client.call(
              'getExtendedMetadataText',
              [('id', item_id), ('type', metadata_type)])
          return response.get('getExtendedMetadataTextResult', None)
docs: Get extended metadata text for a media item.
  
          Args:
              item_id (str): The item for which metadata is required
              metadata_type (str): The type of text to return, eg
              ``'ARTIST_BIO'``, or ``'ALBUM_NOTES'``. Calling
              `get_extended_metadata` for the item will show which extended
              metadata_types are available (under relatedBrowse and relatedText).
  
          Returns:
              str: The item's extended metadata text or None
  
          See also:
              The Sonos `getExtendedMetadataText API
              <http://musicpartners.sonos.com/node/127>`_