@abc.abstractmethod<EOL><INDENT>def get_spatial_unit(self):<DEDENT>
return<EOL>
Gets the spatial unit corresponding to this location.

        :return: the spatial unit for this location
        :rtype: ``osid.mapping.SpatialUnit``
        :raise: ``IllegalState`` -- ``has_spatial_unit()`` is ``false``

        *compliance: mandatory -- This method must be implemented.*