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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_session(self):
 """ S3 Boto3 Session. Returns: boto3.session.Session: session """

        if self._session is None:
            self._session = _boto3.session.Session(
                **self._storage_parameters.get('session', dict()))
        return self._session