def save(self, *args, **kwargs):
super(Layer, self).save(*args, **kwargs)<EOL>if self.pk and self.is_published != self._current_is_published:<EOL><INDENT>layer_is_published_changed.send(<EOL>sender=self.__class__,<EOL>instance=self,<EOL>old_is_published=self._current_is_published,<EOL>new_is_published=self.is_published<EOL>)<EOL>self.update_nodes_published()<EOL><DEDENT>self._current_is_published = self.is_published<EOL>
intercepts changes to is_published and fires layer_is_published_changed signal