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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_asset_temporal_session(self):
 """Gets the session for retrieving temporal coverage of an asset. return: (osid.repository.AssetTemporalSession) - an AssetTemporalSession raise: OperationFailed - unable to complete request raise: Unimplemented - supports_asset_temporal() is false compliance: optional - This method must be implemented if supports_asset_temporal() is true. """

        if not self.supports_asset_temporal():
            raise Unimplemented()
        try:
            from . import sessions
        except ImportError:
            raise  # OperationFailed()
        try:
            session = sessions.AssetTemporalSession(proxy=self._proxy,
                                                    runtime=self._runtime)
        except AttributeError:
            raise  # OperationFailed()
        return session