def get_conf(cls, builder, doctree=None):
        """Return a dictionary of slide configuration for this doctree."""

        # set up the default conf
        result = {
            'theme': builder.config.slide_theme,
            'autoslides': builder.config.autoslides,
            'slide_classes': [],
        }

        # now look for a slideconf node in the doctree and update the conf
        if doctree:
            conf_node = cls.get(doctree)
            if conf_node:
                result.update(conf_node.attributes)

        return result
Return a dictionary of slide configuration for this doctree.