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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 state(self) -> SessionState: """The state of the managed Spark session."""

        if self.session_id is None:
            raise ValueError("session not yet started")
        session = self.client.get_session(self.session_id)
        if session is None:
            raise ValueError("session not found - it may have been shut down")
        return session.state