docs: def get_log(self, target_dir=None, log_filename='log.txt'):
          """
          Retrieve the log of the service execution.
  
          .. versionadded:: 1.13
  
          :param target_dir: (optional) directory path name where the store the log.txt to.
          :type target_dir: basestring or None
          :param log_filename: (optional) log filename to write the log to, defaults to `log.txt`.
          :type log_filename: basestring or None
          :raises APIError: if the logfile could not be found.
          :raises OSError: if the file could not be written.
          """
          full_path = os.path.join(target_dir or os.getcwd(), log_filename)
  
          url = self._client._build_url('service_execution_log', service_execution_id=self.id)
          response = self._client._request('GET', url)
          if response.status_code != requests.codes.ok:  # pragma: no cover
              raise APIError("Could not download service execution log")
  
          with open(full_path, 'w+b') as f:
              for chunk in response:
                  f.write(chunk)