@abc.abstractmethod<EOL><INDENT>def entered_spatial_unit(self, notification_id, resource_id, spatial_unit):<DEDENT>
pass<EOL>
The callback for notifications of resources entering spatial units.

        :param notification_id: the notification ``Id``
        :type notification_id: ``osid.id.Id``
        :param resource_id: the ``Id`` of the ``Resource``
        :type resource_id: ``osid.id.Id``
        :param spatial_unit: the ``Id`` of the ``SpatialUnit``
        :type spatial_unit: ``osid.mapping.SpatialUnit``


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