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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_text(self, item_id, metadata_type):
 """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>`_ """

        response = self.soap_client.call(
            'getExtendedMetadataText',
            [('id', item_id), ('type', metadata_type)])
        return response.get('getExtendedMetadataTextResult', None)