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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 update_asset_ddo(self, did, ddo):
 """ Update the ddo of a did already registered. :param did: Asset DID string :param ddo: DDO instance :return: API response (depends on implementation) """

        response = self.requests_session.put(f'{self.url}/{did}', data=ddo.as_text(),
                                             headers=self._headers)
        if response.status_code == 200 or response.status_code == 201:
            return json.loads(response.content)
        else:
            raise Exception(f'Unable to update DDO: {response.content}')