'Receive an object instance before that instance is deleted.
Note that *no* changes to the overall flush plan can be made
here; and manipulation of the ``Session`` will not have the
desired effect. To manipulate the ``Session`` within an
extension, use ``SessionExtension``.
The return value is only significant within the ``MapperExtension``
chain; the parent mapper\'s behavior isn\'t modified by this method.'

def before_delete(self, mapper, connection, instance):

    return EXT_CONTINUE
