def get_asset_spatial_session(self):
raise Unimplemented()<EOL>
Gets the session for retrieving spatial coverage of an asset.

        return: (osid.repository.AssetSpatialSession) - an
                ``AssetSpatialSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_spatial_assets()`` is
                ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_spatial_assets()`` is ``true``.*