Gets the session for retrieving asset to repository mappings.

        arg     proxy (osid.proxy.Proxy): a proxy
        return: (osid.repository.AssetRepositorySession) - an
                AssetRepositorySession
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - supports_asset_repository() is false
        compliance: optional - This method must be implemented if
                    supports_asset_repository() is true.

def get_asset_repository_session(self, proxy):
        """Gets the session for retrieving asset to repository mappings.

        arg     proxy (osid.proxy.Proxy): a proxy
        return: (osid.repository.AssetRepositorySession) - an
                AssetRepositorySession
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - supports_asset_repository() is false
        compliance: optional - This method must be implemented if
                    supports_asset_repository() is true.

        """
        if not self.supports_asset_repository():
            raise Unimplemented()
        try:
            from . import sessions
        except ImportError:
            raise  # OperationFailed()
        proxy = self._convert_proxy(proxy)
        try:
            session = sessions.AssetRespositorySession(proxy, runtime=self._runtime)
        except AttributeError:
            raise  # OperationFailed()
        return session